However, such a press would be complex and difficult to manufacture. The BARS apparatus is claimed to be the most compact, efficient, and economical of all the diamond-producing presses. In the center of a BARS device, there is a ceramic cylindrical "synthesis capsule" of about 2 cm in size. The cell is placed into a cube of pressure-transmitting material, such as pyrophyllite ceramics, which is pressed by inner anvils made from cemented carbide (e.g., tungsten carbide or VK10 hard alloy). The outer octahedral cavity is pressed by 8 steel outer anvils. After mounting, the whole assembly is locked in a disc-type barrel with a diameter about 1 meter.
High pressure, high temperature
Synthetic diamond
Synthetic diamond | High pressure, high temperature
Pure carbon, the belt press, the cubic press and the split-sphere (BARS) press. Pure carbon crystallized in an isotropic 3D form Pure carbon, crystallized in an isotropic 3D form. Pure carbon
when was the first man made diamond made
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1954
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what are the materials required to make this?
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In the HPHT method, there are three main press designs used to supply the pressure and temperature necessary to produce synthetic diamond: the belt press, the cubic press and the split-sphere (BARS) press. Diamond seeds are placed at the bottom of the press. The internal part of press is heated above 1400 °C and melts the solvent metal. The molten metal dissolves the high purity carbon source, which is then transported to the small diamond seeds and precipitates, forming a large synthetic diamond. The original GE invention by Tracy Hall uses the belt press wherein the upper and lower anvils supply the pressure load to a cylindrical inner cell.
Synthetic diamond | High pressure, high temperature
The high-pressure synthesis of diamond in 1953 in Sweden and in 1954 in the US, made possible by the development of new apparatus and techniques, became a milestone in synthesis of artificial superhard materials. The synthesis clearly showed the potential of high-pressure applications for industrial purposes and stimulated growing interest in the field. Four years after the first synthesis of artificial diamond, cubic boron nitride c-BN was obtained and found to be the second hardest solid. Synthetic diamond can exist as a single, continuous crystal or as small polycrystals interconnected through the grain boundaries. The inherent spatial separation of these subunits causes the formation of grains, which are visible by the unaided eye due to the light absorption and scattering properties of the material.
Superhard material | Synthetic diamond
Bundy and Strong made the first improvements, then more were made by Hall. The GE team used tungsten carbide anvils within a hydraulic press to squeeze the carbonaceous sample held in a catlinite container, the finished grit being squeezed out of the container into a gasket. The team recorded diamond synthesis on one occasion, but the experiment could not be reproduced because of uncertain synthesis conditions, and the diamond was later shown to have been a natural diamond used as a seed. Hall achieved the first commercially successful synthesis of diamond on December 16, 1954, and this was announced on February 15, 1955.
Synthetic diamond | GE diamond project
It was known since experiments of Antoine Lavoisier that diamond was a form of carbon. Wells's story appeared a few years after the claims of James Ballantyne Hannay in 1879 and Ferdinand Frédéric Henri Moissan in 1893, that they had made artificial diamonds. Moissan heated charcoal (a form of carbon) and iron in a furnace until the iron melted; then rapidly cooled, the iron would generate high pressure and transform the charcoal into diamonds. Others tried to repeat this experiment in later years, and very small diamonds were created; commercially successful production of synthetic diamonds was not achieved until the 1950s.
The Diamond Maker | Historical background
There are several methods used to produce synthetic diamonds. The original method uses high pressure and high temperature (HPHT) and is still widely used because of its relatively low cost. The process involves large presses that can weigh hundreds of tons to produce a pressure of 5 GPa at 1500 °C. The second method, using chemical vapor deposition (CVD), creates a carbon plasma over a substrate onto which the carbon atoms deposit to form diamond. Other methods include explosive formation (forming detonation nanodiamonds) and sonication of graphite solutions.
Synthetic diamond | Manufacturing technologies
In 1941, an agreement was made between the General Electric (GE), Norton and Carborundum companies to further develop diamond synthesis. They were able to heat carbon to about under a pressure of for a few seconds. Soon thereafter, the Second World War interrupted the project. It was resumed in 1951 at the Schenectady Laboratories of GE, and a high-pressure diamond group was formed with Francis P. Bundy and H. M. Strong. Tracy Hall and others joined the project later. The Schenectady group improved on the anvils designed by Percy Bridgman, who received a Nobel Prize for his work in 1946.
Synthetic diamond | GE diamond project
He left GE in 1955, and three years later developed a new apparatus for the synthesis of diamond—a tetrahedral press with four anvils—to avoid violating a U.S. Department of Commerce secrecy order on the GE patent applications.
Synthetic diamond | GE diamond project
His breakthrough was using a "belt" press, which was capable of producing pressures above and temperatures above . The press used a pyrophyllite container in which graphite was dissolved within molten nickel, cobalt or iron. Those metals acted as a "solvent-catalyst", which both dissolved carbon and accelerated its conversion into diamond. The largest diamond he produced was across; it was too small and visually imperfect for jewelry, but usable in industrial abrasives. Hall's co-workers were able to replicate his work, and the discovery was published in the major journal "Nature". He was the first person to grow a synthetic diamond with a reproducible, verifiable and well-documented process.
Synthetic diamond | GE diamond project
Synthetic diamond (also referred to as laboratory-grown diamond, laboratory-created diamond, or cultured diamond) is a diamond made of the same material as natural diamonds: pure carbon, crystallized in an isotropic 3D form. Synthetic diamond are different from both natural diamond, which is created by geological processes, and imitation diamond, which is made of non-diamond material. Records of attempted diamond synthesis date back to the turn of the twentieth century. Numerous scientists claimed to have successfully synthesized diamonds between 1879 and 1928, but none was confirmed. In the 1940s, systematic research began in the United States, Sweden and the Soviet Union to grow diamonds, which culminated in the first reproducible synthesis of diamond in 1954.
Synthetic diamond | Introduction
After the 1797 discovery that diamond was pure carbon, many attempts were made to convert various cheap forms of carbon into diamond. The earliest successes were reported by James Ballantyne Hannay in 1879 and by Ferdinand Frédéric Henri Moissan in 1893. Their method involved heating charcoal at up to 3500 °C with iron inside a carbon crucible in a furnace. Whereas Hannay used a flame-heated tube, Moissan applied his newly developed electric arc furnace, in which an electric arc was struck between carbon rods inside blocks of lime. The molten iron was then rapidly cooled by immersion in water. The contraction generated by the cooling supposedly produced the high pressure required to transform graphite into diamond.
Synthetic diamond | History
The cubic press was created shortly thereafter to increase the volume to which pressure could be applied. A cubic press is typically smaller than a belt press and can more rapidly achieve the pressure and temperature necessary to create synthetic diamond. However, cubic presses cannot be easily scaled up to larger volumes: the pressurized volume can be increased by using larger anvils, but this also increases the amount of force needed on the anvils to achieve the same pressure. An alternative is to decrease the surface area to volume ratio of the pressurized volume, by using more anvils to converge upon a higher-order platonic solid, such as a dodecahedron.
Synthetic diamond | High pressure, high temperature
He suggested that most diamonds that had been produced up to that point were likely synthetic spinel.
Synthetic diamond | History
Von Platen left the project before it succeeded in producing the first synthetic diamonds in 1953.
Baltzar von Platen (inventor) | Biography
The barrel is filled with oil, which pressurizes upon heating, and the oil pressure is transferred to the central cell. The synthesis capsule is heated up by a coaxial graphite heater and the temperature is measured with a thermocouple.
Synthetic diamond | High pressure, high temperature
However, such a press would be complex and difficult to manufacture. The BARS apparatus is claimed to be the most compact, efficient, and economical of all the diamond-producing presses. In the center of a BARS device, there is a ceramic cylindrical "synthesis capsule" of about 2 cm in size. The cell is placed into a cube of pressure-transmitting material, such as pyrophyllite ceramics, which is pressed by inner anvils made from cemented carbide (e.g., tungsten carbide or VK10 hard alloy). The outer octahedral cavity is pressed by 8 steel outer anvils. After mounting, the whole assembly is locked in a disc-type barrel with a diameter about 1 meter.
Synthetic diamond | High pressure, high temperature
An independent diamond synthesis was achieved on February 16, 1953 in Stockholm by ASEA (Allmänna Svenska Elektriska Aktiebolaget), one of Sweden's major electrical manufacturing companies. Starting in 1949, ASEA employed a team of five scientists and engineers as part of a top-secret diamond-making project code-named QUINTUS. The team used a bulky split-sphere apparatus designed by Baltzar von Platen and Anders Kämpe. Pressure was maintained within the device at an estimated 8.4 GPa for an hour. A few small diamonds were produced, but not of gem quality or size. The work was not reported until the 1980s. During the 1980s, a new competitor emerged in Korea, a company named Iljin Diamond; it was followed by hundreds of Chinese enterprises.
Synthetic diamond | Later developments
Iljin Diamond allegedly accomplished diamond synthesis in 1988 by misappropriating trade secrets from GE via a Korean former GE employee. Synthetic gem-quality diamond crystals were first produced in 1970 by GE, then reported in 1971. The first successes used a pyrophyllite tube seeded at each end with thin pieces of diamond. The graphite feed material was placed in the center and the metal solvent (nickel) between the graphite and the seeds. The container was heated and the pressure was raised to about 5.5 GPa. The crystals grow as they flow from the center to the ends of the tube, and extending the length of the process produces larger crystals.
Synthetic diamond | Later developments
James Ballantyne Hannay FRSE(1855–1931) was a Scottish chemist who believed he had synthesized diamond in 1880. However, modern testing showed that the surviving samples from his experiments were natural diamond, not synthetic. While his techniques were conducive to diamond formation, modern diamond production – not achieved until the 1950s – requires capabilities not available in Hannay's time. Hannay was also known for making precision instruments.
James Ballantyne Hannay | Introduction
Initially, a week-long growth process produced gem-quality stones of around 5 mm (1 carat or 0.2 g), and the process conditions had to be as stable as possible. The graphite feed was soon replaced by diamond grit because that allowed much better control of the shape of the final crystal. The first gem-quality stones were always yellow to brown in color because of contamination with nitrogen. Inclusions were common, especially "plate-like" ones from the nickel. Removing all nitrogen from the process by adding aluminium or titanium produced colorless "white" stones, and removing the nitrogen and adding boron produced blue ones.
Synthetic diamond | Later developments
Synthetic diamonds are produced via high pressure, high temperature (HPHT) or chemical vapor deposition (CVD) technology. These diamonds have numerous industrial and commercial uses including cutting tools, thermal conductors and consumer diamond gemstones.
List of synthetic diamond manufacturers | Introduction
Howard Tracy Hall (October 20, 1919 – July 25, 2008) was an American physical chemist and the first person who grew a synthetic diamond by a reproducible, verifiable, and witnessed process, using a press of his own design.
Tracy Hall | Introduction
This early research of diamond synthesis in the U.S., Sweden and the Soviet Union yielded the discovery of the CVD diamond (chemical vapor deposition) and HPHT diamond (high-pressure high-temperature) processes. These two processes still dominate the production of synthetic diamond, but researchers have since discovered a third and fourth method of diamond synthesis. A third method, known as detonation synthesis, entered the diamond market in the late 1990s. In this process, the detonation of carbon-containing explosives creates nanometer-sized diamond grains. Scientists have also demonstrated a fourth method of diamond synthesis, treating graphite with high-power ultrasound, but this process currently has no commercial application.
Synthetic diamond | Introduction
This internal pressure is confined radially by a belt of pre-stressed steel bands. The anvils also serve as electrodes providing electric current to the compressed cell. A variation of the belt press uses hydraulic pressure, rather than steel belts, to confine the internal pressure. Belt presses are still used today, but they are built on a much larger scale than those of the original design. The second type of press design is the cubic press. A cubic press has six anvils which provide pressure simultaneously onto all faces of a cube-shaped volume. The first multi-anvil press design was a tetrahedral press, using four anvils to converge upon a tetrahedron-shaped volume.
Synthetic diamond | High pressure, high temperature
Percy Williams Bridgman received a Nobel Prize in 1946 for advancing this area of physics by several magnitudes of pressure (400 MPa to 40,000 MPa). The list of founding fathers of this field includes also the names of Harry George Drickamer, Tracy Hall, Francis P. Bundy, Leonid F. Vereschagin, and Sergey M. Stishov. It was by applying high pressure as well as high temperature to carbon that man-made diamonds were first produced as well as many other interesting discoveries. Almost any material when subjected to high pressure will compact itself into a denser form, for example, quartz, also called silica or silicon dioxide will first adopt a denser form known as coesite, then upon application of even higher pressure, form stishovite.
High pressure | History and overview
A prominent scientist and engineer known for his invention of the steam turbine, he spent about 40 years (1882–1922) and a considerable part of his fortune trying to reproduce the experiments of Moissan and Hannay, but also adapted processes of his own. Parsons was known for his painstakingly accurate approach and methodical record keeping; all his resulting samples were preserved for further analysis by an independent party. He wrote a number of articles—some of the earliest on HPHT diamond—in which he claimed to have produced small diamonds. However, in 1928, he authorized Dr. C. H. Desch to publish an article in which he stated his belief that no synthetic diamonds (including those of Moissan and others) had been produced up to that date.
Synthetic diamond | History
synthetic diamonds, invented in the 1950s, found almost immediate industrial applications; 3 billion carats (600 tonnes) of synthetic diamond is produced annually.
Carbon | Diamonds
Moissan published his work in a series of articles in the 1890s. Many other scientists tried to replicate his experiments. Sir William Crookes claimed success in 1909. Otto Ruff claimed in 1917 to have produced diamonds up to 7 mm in diameter, but later retracted his statement. In 1926, Dr. J Willard Hershey of McPherson College replicated Moissan's and Ruff's experiments, producing a synthetic diamond; that specimen is on display at the McPherson Museum in Kansas. Despite the claims of Moissan, Ruff, and Hershey, other experimenters were unable to reproduce their synthesis. The most definitive replication attempts were performed by Sir Charles Algernon Parsons.
Synthetic diamond | History
The company developed five generations of plasma reactor designs using software simulations of plasma physics to develop its technology for managing a high-density plasma for diamond growth at extremely high temperatures. As contrasted with diamond simulants (which are non-diamond material that appears similar to diamond) and natural mined diamonds, synthetic diamonds are actual diamonds that are produced by a manufacturing process. The company "grows" diamond using the chemical vapor deposition (CVD) method, by placing a small piece of natural diamond in a plasma reactor for a period of about two weeks. The resulting man-made diamond is essentially identical to natural diamond (atomically, molecularly, chemically, visually, in terms of hardness, optical brilliance, crystalline structure, etc.) but without the resource intensiveness, hazards, and environmental concerns that occur with diamond mining.
Diamond Foundry | Technology
As De Beers Industrial Diamond, the company was set up initially to concentrate on the industrial applications of natural diamond. Following the development of diamond synthesis in the early 1950s, the company acquired the technology and by 1958 was able to manufacture material based on a high pressure, high temperature process. By the 1960s, the company was offering a range of diamond grit products that was followed by nickel and coated diamond materials plus grinding products based on cubic boron nitride. In 1992, breakthroughs in chemical vapour deposition technology opened the opportunity to synthesize diamond films and a new raft of application areas became possible.
Element Six | History
Typically, diamond is formed by heating carbon at very high temperatures (>5,000 K) and pressures (>120,000 atmospheres). However, Narayan and his group used kinetics and time control of pulsed nanosecond laser melting to overcome thermodynamic limitations and create a supercooled state that enables conversion of carbon into Q-carbon and diamond at ambient temperatures and pressures. The process uses a high-powered laser pulse, similar to that used in eye surgery, lasting approximately 200 nanoseconds. This raises the temperature of the carbon to approximately 4,000 K (3,700 °C; 6,700 °F) at atmospheric pressure. The resulting liquid is then quenched (rapidly cooled); it is this stage that is the source of the "Q" in the material's name.
Amorphous carbon | Production
Since the 1950s, techniques can produce diamonds of essentially any desired chemistry or size. Although some manufacturers do label their synthetic diamonds with serial numbers there is no guarantee that a given diamond is not man made, although sometimes an unnatural chemical composition or pattern of flaws may suggest a diamond is synthetic. It is much cheaper to produce diamonds through artificial synthesis than to mine them, although currently the cost of synthesis is still significant. The inability to guarantee that a diamond is naturally occurring could undermine the premium price still currently charged over synthetic diamonds. However, new technological advances have allowed some independent gem labs such as GIA (Gemological Institute of America) to issue a specific Synthetic Diamond Grading Report which identifies a diamond as laboratory-grown and laser inscribes it with "laboratory grown".
Diamonds as an investment | Synthetic diamonds
However, synthetic rutile in a range of different colors, including blues and reds, were produced using various metal oxide dopants. These and the near-white stones were extremely popular if unreal stones. Synthetic rutile is also fairly soft (hardness ~6) and brittle, and therefore wears poorly. It is synthesized via a modification of the Verneuil process, which uses a third oxygen pipe to create a "tricone burner"; this is necessary to produce a single crystal, due to the much higher oxygen losses involved in the oxidation of titanium. The technique was invented by Charles H. Moore, Jr. at the South Amboy, New Jersey-based National Lead Company (later NL Industries).
Diamond simulant | 1947–1970
The majority of commercially available synthetic diamonds are yellow and are produced by so-called "high-pressure high-temperature" (HPHT) processes. The yellow color is caused by nitrogen impurities. Other colors may also be reproduced such as blue, green or pink, which are a result of the addition of boron or from irradiation after synthesis. Another popular method of growing synthetic diamond is chemical vapor deposition (CVD). The growth occurs under low pressure (below atmospheric pressure). It involves feeding a mixture of gases (typically to hydrogen) into a chamber and splitting them to chemically active radicals in a plasma ignited by microwaves, hot filament, arc discharge, welding torch or laser.
Diamond | Synthetics
A professor invents a way of manufacturing diamonds.
The Man Who Made Diamonds | Plot summary
Hall left GE in 1955 and became a full professor of chemistry and Director of Research at Brigham Young University. At BYU, he invented the tetrahedral and Cubic press systems. He transferred the technology for the cubic press system to China in about 1960, and today the vast majority of the world's synthetic diamond powder is produced using the many thousands of cubic presses of Hall's design presently operating in that country. For many years, the first tetrahedral press was displayed in the Eyring Science center on campus at BYU. In the early 1960s, Hall invented the first form of polycrystalline diamond (PCD).
Tracy Hall | Later years
On 12 February 1898, the school was officially christened "McPherson College." In 1926, J Willard Hershey synthesized one of the world's earliest synthetic (man-made) diamonds on the McPherson College campus. Reporting on his experiments, Hershey wrote, "Since we first began our experiments in their manufacture more than 50 diamonds have been made synthetically at McPherson College, ranging in size from the smallest, one millimeter (about 1/25 inch) in diameter, to the largest, which, is two millimeters by one and one half millimeters by one millimeter, weighing 1/30 carat." One of the diamonds is on display at the McPherson Museum in McPherson, Kansas.
McPherson College | History
Cubic boron nitride or c-BN was first synthesized in 1957 by Robert H. Wentorf at General Electric, shortly after the synthesis of diamond. The general process for c-BN synthesis is the dissolution of hexagonal boron nitride (h-BN) in a solvent-catalyst, usually alkali or alkaline earth metals or their nitrides, followed by spontaneous nucleation of c-BN under high pressure, high temperature (HPHT) conditions. The yield of c-BN is lower and substantially slower compared to diamond's synthetic route due to the complicated intermediate steps. Its insolubility in iron and other metal alloys makes it more useful for some industrial applications than diamond.
Superhard material | History
The hardness of synthetic diamond (70–150 GPa) is very dependent on the relative purity of the crystal itself. The more perfect the crystal structure, the harder the diamond becomes. It has been reported that HPHT single crystals and nanocrystalline diamond aggregates (aggregated diamond nanorods) can be harder than natural diamond.
Superhard material | Synthetic diamond
Kelley experimented with several formulas and processes for making synthetic artificial gems. One method involved using temperature difference techniques to create crystals in a way water icicles are formed. One of these man-made gemstones made this way was a transparent clear crystal resembling glass. It looked to the naked eye like a real diamond when faceted correctly and no glass was involved in its manufacture. A second technique involves small pieces ("seeds") of mined gems put into a heated up chemical liquid. The liquid then is slowly cooled, and recrystallized to form larger pieces of the gemstone. Man-made gemstones grow from these "seeds." Kelley's technical success in growing crystals led to the founding of the Shelby Gem Factory in 1970.
Larry Paul Kelley | Shelby Gem Factory
Diamond transistors have been produced (for research purposes). FETs with SiN dielectric layers, and SC-FETs have been made. In April 2004, the journal Nature reported that below the superconducting transition temperature 4 K, boron-doped diamond synthesized at high temperature and high pressure is a bulk superconductor. Superconductivity was later observed in heavily boron-doped films grown by various chemical vapor deposition techniques, and the highest reported transition temperature (by 2009) is 11.4 K. (See also Covalent superconductor#Diamond)
Material properties of diamond | Electrical properties
In 1772, the French scientist Antoine Lavoisier used a lens to concentrate the rays of the sun on a diamond in an atmosphere of oxygen, and showed that the only product of the combustion was carbon dioxide, proving that diamond is composed of carbon. Later in 1797, the English chemist Smithson Tennant repeated and expanded that experiment. By demonstrating that burning diamond and graphite releases the same amount of gas, he established the chemical equivalence of these substances.
Diamond | Etymology, earliest use and composition discovery
In 1919, Lazare Kaplan's cousin, mathematician Marcel Tolkowsky, first published the mathematical formula for diamonds cut to "ideal" proportions, a formula designed to optimise the brilliance, fire and sparkle in a polished diamond. In the same year, LKI became the first commercial-scale operation to cut its diamonds to ideal proportions. In 1957, LKI developed the modern oval cut, and in 1983 it developed and patented the laser inscription process. In 2002, LKI was awarded a patent, jointly with the General Electric Company, for the high-pressure high-temperature (HPHT) process for improving the color of certain all-natural diamond types. In addition, LKI has secured numerous patents on diamond setting techniques and innovations in displays for loose polished stones and jewelry.
Lazare Kaplan International | Technical innovation
These characteristic properties are attributed to the diamond-like structure combined with the sp3 σ-bonds among carbon and the heteroatoms. BCN thin films were synthesized by chemical vapor deposition in 1972. However, data on the attempted synthesis of B-C-N dense phases reported by different authors have been contradictory. It is unclear whether the synthesis products are diamond-like solid solutions between carbon and boron nitride or just mechanical mixtures of highly dispersed diamond and c-BN. In 2001, a diamond-like-structured c-BCN was synthesized at pressures >18 GPa and temperatures >2,200 K by a direct solid-state phase transition of graphite-like (BN)C. The reported Vickers and Knoop hardnesses were intermediate between diamond and c-BN, making the new phase the second hardest known material.
Superhard material | Boron carbon nitride
The similar atomic sizes of boron, carbon and nitrogen, as well as the similar structures of carbon and boron nitride polymorphs, suggest that it might be possible to synthesize diamond-like phase containing all three elements. It is also possible to make compounds containing B-C-O, B-O-N, or B-C-O-N under high pressure, but their synthesis would expect to require a complex chemistry and in addition, their elastic properties would be inferior to that of diamond. Beginning in 1990, a great interest has been put in studying the possibility to synthesize dense B-C-N phases. They are expected to be thermally and chemically more stable than diamond, and harder than c-BN, and would therefore be excellent materials for high speed cutting and polishing of ferrous alloys.
Superhard material | Boron carbon nitride
Synthetic diamonds are diamonds manufactured in a laboratory, as opposed to diamonds mined from the Earth. The gemological and industrial uses of diamond have created a large demand for rough stones. This demand has been satisfied in large part by synthetic diamonds, which have been manufactured by various processes for more than half a century. However, in recent years it has become possible to produce gem-quality synthetic diamonds of significant size. It is possible to make colorless synthetic gemstones that, on a molecular level, are identical to natural stones and so visually similar that only a gemologist with special equipment can tell the difference.
Diamond | Synthetics
Diamond is an allotrope of carbon where the atoms are arranged in a modified version of face-centered cubic ("fcc") structure known as "diamond cubic". It is known for its hardness (see table above) and incompressibility and is targeted for some potential optical and electrical applications. The properties of individual natural diamonds or carbonado vary too widely for industrial purposes, and therefore synthetic diamond became a major research focus.
Superhard material | Diamond
The inventors, respondents, filed a patent application for a "[process] for molding raw, uncured synthetic rubber into cured precision products." The process of curing synthetic rubber depends on a number of factors including time, temperature and thickness of the mold. Using the Arrhenius equation formula_1 which may be restated as "ln"("v") = "CZ" + "x" it is possible to calculate when to open the press and to remove the cured, molded rubber. The problem was that there was, at the time the invention was made, no disclosed way to obtain an accurate measure of the temperature without opening the press.
Diamond v. Diehr | The problem and its solution
The first crystalline artificial diamond simulants were synthetic white sapphire (AlO, pure corundum) and spinel (MgO·AlO, pure magnesium aluminium oxide). Both have been synthesized in large quantities since the first decade of the 20th century via the Verneuil or flame-fusion process, although spinel was not in wide use until the 1920s. The Verneuil process involves an inverted oxyhydrogen blowpipe, with purified feed powder mixed with oxygen that is carefully fed through the blowpipe. The feed powder falls through the oxy-hydrogen flame, melts, and lands on a rotating and slowly descending pedestal below. The height of the pedestal is constantly adjusted to keep its top at the optimal position below the flame, and over a number of hours the molten powder cools and crystallizes to form a single pedunculated pear or "boule" crystal.
Diamond simulant | 1900–1947
For economic reasons, the growth of most synthetic diamonds is terminated when they reach a mass of to .
Synthetic diamond | Later developments
The development of laser heating began only 8 years after Charles Weir, of the National Bureau of Standards (NBS), made the first diamond anvil cell and Alvin Van Valkenburg, NBS, realized the potential of being able to see the sample while under pressure. William Bassett and his colleague Taro Takahashi focused a laser beam on the sample while under pressure. The first laser heating system used a single 7 joule pulsed ruby laser that heated the sample to 3000 °C while at 260 kilobars. This was sufficient to convert graphite to diamond. The major flaws within the first system related to control and temperature measurement.
Diamond anvil cell | History
After a failed experiment that involved compressing a sample with a diamond piston inserted into a cylindrical hole bored into a 7.5 carat diamond crystal, Weir proposed an opposed anvil device that would take advantage of the high compressive strength of diamond (as opposed to its less impressive tensile strength) to perform infrared absorption measurements at high pressure. In 1958, Weir took the lead role in designing the first diamond anvil cell, and fabricated it himself using the tools available to him in the laboratory.
Charles E. Weir | Career
Diamane is a 2D form of diamond. It can be made via high pressures, but without that pressure, the material reverts to graphene. Another technique is to add hydrogen atoms but those bonds are weak. Using fluorine (xenon-difluoride) instead brings the layers closer together, strengthening the bonds. This is called f-diamane.
Allotropes of carbon | Diamane
Nitrogen impurities hinder movement of lattice dislocations (defects within the crystal structure) and put the lattice under compressive stress, thereby increasing hardness and toughness.
Synthetic diamond | Impurities and inclusions
Synthetic diamonds created by compressing graphite to several gigapascals and heating to temperatures above 1500 °C are usually rich in nitrogen. Nitrogen in those diamonds is dispersed through the lattice as single atoms and induces yellow color. Nickel is often added to graphite to accelerate its conversion into diamond. Incorporation of nickel and nitrogen into diamond induces brown color. Nickel is easily detectable by characteristic, sharp optical absorption and luminescence signals making such diamonds easily identifiable.
Brown diamonds | Brown synthetic diamonds
Recent advances in the HPHT and CVD synthesis techniques have improved the purity and crystallographic structure perfection of single-crystalline diamond enough to replace silicon as a diffraction grating and window material in high-power radiation sources, such as synchrotrons. Both the CVD and HPHT processes are also used to create designer optically transparent diamond anvils as a tool for measuring electric and magnetic properties of materials at ultra high pressures using a diamond anvil cell.
Synthetic diamond | Optical material
Robert H. Wentorf Jr. (May 28, 1926 in West Bend, Wis. – April 3, 1997 in Easton, N.Y.) was a staff scientist at General Electric Corporate Research and Development Laboratory in Schenectady, N.Y. and a professor of chemical engineering at Rensselaer Polytechnic Institute in Troy, N.Y. Wentorf was a chemical engineer and physical chemist who specialized in the synthesis of diamond and other superhard materials under conditions of high temperature and pressure. He is best known as the inventor of cubic boron nitride (trade name, "Borazon"), the second-hardest material known. Borazon is used industrially as a substitute for diamond where chemical reactivity or high temperature is a problem in grinding or cutting.
Robert H. Wentorf Jr. | Introduction
Diamond nanocrystals (5 nm in diameter) can be formed by detonating certain carbon-containing explosives in a metal chamber. These nanocrystals are called "detonation nanodiamonds". During the explosion, the pressure and temperature in the chamber become high enough to convert the carbon of the explosives into diamond. Being immersed in water, the chamber cools rapidly after the explosion, suppressing conversion of newly produced diamond into more stable graphite. In a variation of this technique, a metal tube filled with graphite powder is placed in the detonation chamber. The explosion heats and compresses the graphite to an extent sufficient for its conversion into diamond.
Synthetic diamond | Detonation of explosives
It is reasonable to envisage the process as a "hail" of projectiles that produce localized, faster, nanoscale versions of the classic combinations of heat and pressure that produce natural and synthetic diamond. Because they occur independently at many places across the surface of a growing film or coating, they tend to produce an analog of a cobblestone street with the cobbles being nodules or clusters of sp bonded carbon. Depending upon the particular "recipe" being used, there are cycles of deposition of carbon and impact or continuous proportions of new carbon arriving and projectiles conveying the impacts needed to force the formation of the sp bonds.
Diamond-like carbon | Production
The first lab-made diamonds can be dated back to the 1950s, while memorial diamonds started to appear in the market in the early 2000s. More than one company has claimed to be the first to provide memorial diamonds, and both Heart In Diamond and LifeGem have claimed to have a patent covering the growing of a "personalized gem diamond".
Memorial diamond | History
In 1796 Smithson Tennant was experimenting on diamonds when he decided to burn one. Using only sunlight and a magnifying glass he managed to ignite a diamond sufficiently for it to produce a gas, which he collected and was able to identify as carbon dioxide. Having started with only diamond and oxygen, and produced a gas which contains only carbon and oxygen, Tennant had discovered that diamonds are made of carbon. Unaware of atomic theory at the time, scientists were unable to explain how carbon, already known to exist as one of the softest substances in the form of graphite, could also be the sole constituent element of the hardest known substance: diamond.
Chemistry: A Volatile History | Smithson Tennant discovers what diamonds are made of
The first of the optically "improved" simulants was synthetic rutile (TiO, pure titanium oxide). Introduced in 1947–48, synthetic rutile possesses plenty of life when cut—perhaps too much life for a diamond simulant. Synthetic rutile's RI and dispersion (2.8 and 0.33) are so much higher than diamond that the resultant brilliants look almost opal-like in their display of prismatic colors. Synthetic rutile is also doubly refractive: although some stones are cut with the table perpendicular to the optic axis to hide this property, merely tilting the stone will reveal the doubled back facets. The continued success of synthetic rutile was also hampered by the material's inescapable yellow tint, which producers were never able to remedy.
Diamond simulant | 1947–1970
"The Diamond Maker" is a short story by H. G. Wells, first published in 1894 in the "Pall Mall Budget". It was included in "The Stolen Bacillus and Other Incidents", the first collection of short stories by Wells, published in 1895. In the story, a businessman hears an account from a man who has devoted years attempting to make artificial diamonds, only to end as a desperate outcast.
The Diamond Maker | Introduction
In contemporary production it is more common for glass to be molded rather than cut into shape: in these stones the facets will be concave and facet edges rounded, and mold marks or seams may also be present. Glass has also been combined with other materials to produce composites.
Diamond simulant | 1700 onwards
In 1974, Boart International invested capital which helped Longyear to become the world's leading manufacturer of diamond bits. Boart Longyear engineers in North Bay, Ontario, secured a reliable source of high-performance synthetic diamonds, which triggered the development of a new bit design – the impregnated-diamond bit. With decades of powder metallurgy experience behind them, Longyear engineers set out to develop a new crown that consisted of synthetic diamonds evenly distributed throughout a composite matrix. This new design could drill further and faster than surface-set bits and cut through much harder material. By 1980, 75 percent of Longyear's Canadian-produced bits were of the new impregnated type, and Longyear was manufacturing diamond bits in more than eight countries.
Boart Longyear | 1974 to 2000
In 1981, Marvin Ross wrote a paper titled "The ice layer in Uranus and Neptune—diamonds in the sky?" in which he proposed that huge quantities of diamonds might be found in the interior of these planets. At Lawrence Livermore, he had analyzed data from shock-wave compression of methane (CH) and found that the extreme pressure separated the carbon atom from the hydrogen, freeing it to form diamond. Theoretical modeling by Sandro Scandolo and others predicted that diamonds would form at pressures over 300 gigapascals (GPa), but even at lower pressures methane would be disrupted and form chains of hydrocarbons. High pressure experiments at the University of California Berkeley using a diamond anvil cell found both phenomena at only 50 GPa and a temperature of 2500 kelvins, equivalent to depths of 7000 kilometers below Neptune's cloud tops.
Extraterrestrial diamonds | Solar System
Nanodiamond or hyperdiamond was convincingly demonstrated to be produced by compression of graphite in 2003 and in the same work found to be much harder than bulk diamond. Later it was also produced by compression of fullerene and confirmed to be the hardest and least compressible known material, with an isothermal bulk modulus of 491 gigapascals (GPa), while a conventional diamond has a modulus of 442–446 GPa; these results were inferred from X-ray diffraction data, which also indicated that ADNRs are 0.3% denser than regular diamond. The same group later described ADNRs as "having a hardness and Young's modulus comparable to that of natural diamond, but with 'superior wear resistance'".
Aggregated diamond nanorod | Discovery
Used in so-called diamond anvil experiments to create high-pressure environments, diamonds are able to withstand crushing pressures in excess of 600 gigapascals (6 million atmospheres).
Material properties of diamond | Pressure resistance
Removing nitrogen also slowed the growth process and reduced the crystalline quality, so the process was normally run with nitrogen present. Although the GE stones and natural diamonds were chemically identical, their physical properties were not the same. The colorless stones produced strong fluorescence and phosphorescence under short-wavelength ultraviolet light, but were inert under long-wave UV. Among natural diamonds, only the rarer blue gems exhibit these properties. Unlike natural diamonds, all the GE stones showed strong yellow fluorescence under X-rays. The De Beers Diamond Research Laboratory has grown stones of up to for research purposes. Stable HPHT conditions were kept for six weeks to grow high-quality diamonds of this size.
Synthetic diamond | Later developments
Diamond is not suitable for machining ferrous alloys at high speeds, as carbon is soluble in iron at the high temperatures created by high-speed machining, leading to greatly increased wear on diamond tools compared to alternatives.
Diamond | Industrial-grade diamonds
Diamond is the hardest known natural material. Diamond may also refer to:
Diamond (disambiguation) | Introduction
Synthetic diamond is the hardest known material, where hardness is defined as resistance to indentation. The hardness of synthetic diamond depends on its purity, crystalline perfection and orientation: hardness is higher for flawless, pure crystals oriented to the [111] direction (along the longest diagonal of the cubic diamond lattice). Nanocrystalline diamond produced through CVD diamond growth can have a hardness ranging from 30% to 75% of that of single crystal diamond, and the hardness can be controlled for specific applications. Some synthetic single-crystal diamonds and HPHT nanocrystalline diamonds (see hyperdiamond) are harder than any known natural diamond.
Synthetic diamond | Hardness
The gasket (made of a metal such as rhenium or tungsten) flows under ultra-high pressure and fills the central hole with fluid to achieve hydrostatic conditions. The tiny sample to be analyzed is compressed between the two opposing culets (tips) of diamond. The gasket is used to maintain the sample's contact with the culets, where the pressure is at a maximum.
Alvin Van Valkenburg | Introduction
The Man Who Made Diamonds is a 1937 British crime film directed by Ralph Ince and starring Noel Madison, James Stephenson and Lesley Brook.
The Man Who Made Diamonds | Introduction
At the time, technology had not yet evolved to guarantee the quality of modern standards, and cutting the diamond was difficult and risky. After weeks of planning, an incision deep was made to enable Asscher to cleave the diamond in one blow. Making the incision alone took four days, and a steel knife broke on the first attempt, but a second knife was fitted into the groove and split it clean in two along one of four possible cleavage planes. In all, splitting and cutting the diamond took eight months, with three people working 14 hours per day to complete the task.
Cullinan Diamond | Cutting process
The product is always rich in graphite and other non-diamond carbon forms and requires prolonged boiling in hot nitric acid (about 1 day at 250 °C) to dissolve them. The recovered nanodiamond powder is used primarily in polishing applications. It is mainly produced in China, Russia and Belarus and started reaching the market in bulk quantities by the early 2000s.
Synthetic diamond | Detonation of explosives
Sir Robert Robertson (17 April 1869 – 28 April 1949) was a British chemist who served as HM Government's Government Chemist between 1921 and 1936. He was the first person to establish that two types of natural diamond existed.
Robert Robertson (chemist) | Introduction
In 1837, Gaudin made the first synthetic rubies by fusing potash alum at a high temperature with a little chromium as a pigment. In 1847, Ebelmen made white sapphire by fusing alumina in boric acid. In 1877, Edmond Frémy and industrial glass-maker Charles Feil made crystal corundum from which small stones could be cut. In 1887, Fremy and Auguste Verneuil manufactured artificial ruby by fusing BaF and AlO with a little chromium at red heat. In 1903, Verneuil announced he could produce synthetic rubies on a commercial scale using this flame fusion process, later also known as the Verneuil process.
Ruby | Synthetic and imitation rubies
As with many important inventions, the circumstances surrounding Hall's synthesis is the object of some controversy. What is undoubted is that he produced synthetic diamond in a press of his own design on December 16, 1954 and that he and others could do it over and over in the following week and that success led to the creation of a major super materials industry. What is also undoubted is that Hall was one of a group of about a half dozen of researchers who had focused on the syntheses for almost four years. These years had seen a succession of failed experiments, an increasingly impatient management, and a complex blend of sharing and rivalries among the researchers.
Tracy Hall | The invention
The isotopes of carbon can be separated in the form of carbon dioxide gas by cascaded chemical exchange reactions with amine carbamate. Such CO can be converted to methane and from there to isotopically pure synthetic diamonds. Isotopically enriched diamonds have been synthesized by application of chemical vapor deposition followed by high pressure.
Isotopically pure diamond | Manufacture
Asscher’s grandfather founded the Asscher Diamond Company (now the Royal Asscher Diamond Company) in 1854, but it was Abraham and his brother Joseph who built its international fame. In 1907 the brothers opened a new factory at 127 Tolstraat in Amsterdam and soon they received a request from King Edward VII of Great Britain to cleave the legendary Cullinan Diamond, the largest rough gem-quality diamond ever found.
Abraham Asscher | Early career
Heterodiamond is a superhard material containing boron, carbon, and nitrogen (BCN). It is formed at high temperatures and high pressures, e.g., by application of an explosive shock wave to a mixture of diamond and cubic boron nitride (c-BN). The heterodiamond is a polycrystalline material coagulated with nano-crystallites and the fine powder is tinged with deep bluish black. The heterodiamond has both the high hardness of diamond and the excellent heat resistance of cubic BN. These characteristic properties are due to the diamond structure combined with the sp σ-bonds among carbon and the hetero atoms. Cubic BCN can be synthesized from graphite-like BCN at pressures above 18 GPa and temperatures higher than 2200 K.
Heterodiamond | Introduction
The patent that issued after the decision was U.S. Patent 4,344,142, "Direct digital control of rubber molding presses." The patent includes 11 method claims, three of which are independent. All method claims relate to molding of physical articles. The only diagrams in the patent are flowcharts. There are no diagrams of machinery. As the dissenting opinion in "Diehr" noted, the patent specification "teaches nothing about the chemistry of the synthetic rubber-curing process, nothing about the raw materials to be used in curing synthetic rubber, nothing about the equipment to be used in the process, and nothing about the significance or effect of any process variable such as temperature, curing time, particular compositions of material, or mold configurations."
Diamond v. Diehr | The patent no 3591.978
But diamonds (spC) are unstable against high temperature (above about ) under atmospheric pressure. The structure gradually changes into spC above this temperature. Thus, diamonds should be reduced under this temperature.
Diamond | Surface property
These stone axes, made predominantly of the mineral corundum (sapphire and ruby in its colorful gem forms) were fashioned as early as 4000 BC, so that they represent the earliest use of the mineral corundum, as well. The finding's media coverage included a front-page article in China's largest English-language newspaper, the China Daily.
Peter Lu | Man's first use of diamond
Natural diamond's conductivity is reduced by 1.1% by the naturally present, which acts as an inhomogeneity in the lattice. Diamond's thermal conductivity is made use of by jewelers and gemologists who may employ an electronic thermal probe to separate diamonds from their imitations. These probes consist of a pair of battery-powered thermistors mounted in a fine copper tip. One thermistor functions as a heating device while the other measures the temperature of the copper tip: if the stone being tested is a diamond, it will conduct the tip's thermal energy rapidly enough to produce a measurable temperature drop. This test takes about 2–3 seconds.
Synthetic diamond | Thermal conductivity
An issue the world's jewellery traders face is that synthetic diamonds, which are cheaper and now very widespread, can be used to defraud consumers of natural diamonds. As synthetic diamond technology becomes more easily accessible it is necessary for consumers, customs, importers, exporters, and government to be sure of the grade and quality of the diamond or gemstone. Synthetic diamonds may be produced by high-pressure, high-temperature (HTPT) method or chemical vapor deposition (CVD) method, which leave their signatures in the composition of the diamond. Research includes investigating techniques to look for these differences and distinguish natural gem stones from artificially produced ones.
Gemmological Institute of India | Research
Rhenium diboride (ReB) is a synthetic superhard material. It was first synthesized in 1962 and re-emerged recently due to hopes of achieving high hardness comparable to that of diamond. The reported ultrahigh hardness has been questioned, although this is a matter of definition as in the initial test rhenium diboride was able to scratch diamond. The production method of this material does not involve high pressures as with other hard synthetic materials, such as cubic boron nitride, which makes production cheap. However, rhenium itself is an expensive metal. The compound is formed from a mixture of rhenium, noted for its resistance to high pressure, and boron, which forms short, strong covalent bonds with rhenium.
Rhenium diboride | Introduction
After contemplating the diamond for almost a year, Winston chose Lazare Kaplan to study the Jonker diamond. Lazare Kaplan was chosen to cut the diamond into several gemstones. The process of examining the diamond to determine the optimal cuts took place over the course of several months. On 27 April 1936, the first cut was made which cut off a 35-carat section, finally ending with the diamond being cut into 13 pieces. The largest piece produced the Jonker I, a 142.90 ct D-color flawless diamond which was later re-cut to 125.35 carats.
The Jonker | Cut
ADNRs (hyperdiamonds/nanodiamonds) are produced by compressing fullerite powder—a solid form of allotropic carbon fullerene—by either of two somewhat similar methods. One uses a diamond anvil cell and applied pressure ~37 GPa without heating the cell. In another method, fullerite is compressed to lower pressures (2–20 GPa) and then heated to a temperature in the range of . Extreme hardness of what now appears likely to have been nanodiamonds was reported by researchers in the 1990s. The material is a series of interconnected diamond nanorods, with diameters of between 5 and 20 nanometres and lengths of around 1 micrometre each. Nanodiamond aggregates ca.
Aggregated diamond nanorod | Synthesis
Coal is formed from buried prehistoric plants, and most diamonds that have been dated are far older than the first land plants. It is possible that diamonds can form from coal in subduction zones, but diamonds formed in this way are rare, and the carbon source is more likely carbonate rocks and organic carbon in sediments, rather than coal.
Diamond | Geology
Stellite soon joined high speed steels as a material for single-point cutters. Although diamond turning had been around for a long time, it was not until these new, expensive metals came about that the idea of cutting inserts became commonly applied in machining. Before this, most single-point cutters were forged entirely of tool steel (then ground at the tip). Now it became more common to attach a separate tip (of one material) to a holder (of another). With the development of commercially available cemented carbide (1920s) and ceramic inserts (post-WWII), this trend accelerated, because carbide and ceramic are even more expensive and even less suited to serving as a shank.
Tool bit | History
Diamond is hard, chemically inert, and has high thermal conductivity and a low coefficient of thermal expansion. These properties make diamond superior to any other existing window material used for transmitting infrared and microwave radiation. Therefore, synthetic diamond is starting to replace zinc selenide as the output window of high-power CO lasers and gyrotrons. Those synthetic polycrystalline diamond windows are shaped as disks of large diameters (about 10 cm for gyrotrons) and small thicknesses (to reduce absorption) and can only be produced with the CVD technique. Single crystal slabs of dimensions of length up to approximately 10 mm are becoming increasingly important in several areas of optics including heatspreaders inside laser cavities, diffractive optics and as the optical gain medium in Raman lasers.
Synthetic diamond | Optical material
Traditionally, the absence of crystal flaws is considered to be the most important quality of a diamond. Purity and high crystalline perfection make diamonds transparent and clear, whereas its hardness, optical dispersion (luster), and chemical stability (combined with marketing), make it a popular gemstone. High thermal conductivity is also important for technical applications. Whereas high optical dispersion is an intrinsic property of all diamonds, their other properties vary depending on how the diamond was created.
Synthetic diamond | Properties
Examples include: One tetramantane isomer is the largest ever diamondoid prepared by organic synthesis using a keto-carbenoid reaction to attach cyclopentane rings. Longer diamondoids have been formed from diamantane dicarboxylic acid. The first-ever isolation of a wide range of diamondoids from petroleum took place in the following steps: a vacuum distillation above 345 °C, the equivalent atmospheric boiling point, then pyrolysis at 400 to 450 °C in order to remove all non-diamondoid compounds (diamondoids are thermodynamically very stable and will survive this pyrolysis) and then a series of high-performance liquid chromatography separation techniques. In one study a tetramantane compound is fitted with thiol groups at the bridgehead positions.
Diamondoid | Examples
The practice is documented among European aristocracy as early as the 15th century, though ruby and sapphire were more desirable gemstones. The modern popularity of diamonds was largely created by De Beers Consolidated Mines, which established the first large-scale diamonds mines in South Africa. Through an advertising campaign beginning in the 1930s and continuing into the mid-20th century, De Beers made diamonds into a key part of the betrothal process and a coveted symbol of status. The diamond's high value has been the driving force behind dictators and revolutionary entities, especially in Africa, using slave and child labor to mine blood diamonds to fund conflicts.
Diamond (gemstone) | Introduction
In synthetic diamond grown by the high-pressure high-temperature synthesis or chemical vapor deposition, defects with symmetry lower than tetrahedral align to the direction of the growth. Such alignment has also been observed in gallium arsenide and thus is not unique to diamond.
Crystallographic defects in diamond | Defect symmetry
It was done secretly, so that others would not copy his work, and so that he could sell his diamonds without it being known that they could be produced in large quantities. After his money ran out he conducted his experiments in cheap lodgings in Kentish Town, and had various menial jobs. He finally succeeded when, using an idea suggested by experiments of Gabriel Auguste Daubrée, he put the mixture which might produce diamonds together with dynamite in a cylinder too strong to burst. However, as he inspected the results a neighbour in the lodgings house, thinking he was a bomb-making anarchist, told him he had called the police.
The Diamond Maker | Story
During the growth, the chamber materials are etched off by the plasma and can incorporate into the growing diamond. In particular, CVD diamond is often contaminated by silicon originating from the silica windows of the growth chamber or from the silicon substrate. Therefore, silica windows are either avoided or moved away from the substrate. Boron-containing species in the chamber, even at very low trace levels, also make it unsuitable for the growth of pure diamond.
Synthetic diamond | Chemical vapor deposition
Above the triple point, the melting point of diamond increases slowly with increasing pressure; but at pressures of hundreds of GPa, it decreases. At high pressures, silicon and germanium have a BC8 body-centered cubic crystal structure, and a similar structure is predicted for carbon at high pressures. At , the transition is predicted to occur at . Research results published in an article in the scientific journal "Nature" in 2010 suggest that at ultrahigh pressures and temperatures (about 10 million atmospheres or 1 TPa and 50,000 °C) diamond behaves as a metallic fluid. The extreme conditions required for this to occur are present in the gas giants of Neptune and Uranus.
Diamond | Thermodynamics
Highest yields from the undisturbed subsurface material (described as kimberlite or volcanic breccia by the U.S. Geological Survey) were two carats per hundred loads (3.5 mg/Mg) in 1908 and about two carats per hundred short tons (4.4 mg/Mg) in 1943−1944. Because equipment of the early period usually included bottom screens with mesh larger than 1/16 inch (1.6 mm), thousands of smaller diamonds were allowed to pass through. The bulk of these ended up in drainage cuts of varying depths all over the field and in the big natural drains on the east and west edges of the diamond-bearing section of the volcanic deposit (approximately of volcanic breccia on the east side of the pipe).
Crater of Diamonds State Park | History