Welcome to October! Lucky babies born this month have their choice of TWO fantastic birthstones – tourmaline and opal. Let’s dig in and learn more about these fascinating gemstones!
What is Opal?
Opal is the product of seasonal rains that drenched dry ground in regions such as Australia’s semi-desert “outback.” The showers soaked deep into ancient underground rock, carrying dissolved silica (a compound of silicon and oxygen) downward. During dry periods, much of the water evaporated, leaving solid deposits of silica in the cracks and between the layers of underground sedimentary rock. The silica deposits formed opal. Source: www.gia.edu It takes roughly 5 million years for silica to solidify into opal!
Precious opals have two basic colors, their background color and their play of color. The background color is caused by impurities within the silica. The other colors are caused by the way silica forms together. When silica spheres fuse together, tiny gaps are created between them that low the light to diffract. This diffraction causes the numerous different color combinations.
Besides being one of October’s birthstones, opal is also the official gemstone gift for the 14th wedding anniversary!
Where is Opal found?
They are found in Australia, Ethiopia, Mexico, Brazil and other locales. Australia’s mines began to produce opals commercially in the 1890s, it quickly became the world’s primary source for this October birthstone.
Because opal has the colors of other gems, the Romans thought it was the most precious and powerful of all. The Bedouins believed that opals contained lightning and fell from the sky during thunderstorms. Many cultures have credited opal with supernatural origins and powers. The ancient Greeks believed opals gave their owners the gift of prophecy and guarded them from disease. Europeans have long considered the gem a symbol of hope, purity, and truth. Source: www.gia.edu
How to Buy Opal
Individual opals can vary widely in appearance and quality. As diverse as snowflakes or fingerprints, each gem can differ noticeably. While there is no ‘formula’ for figuring out the value of an opal, there are some factors that will play a major role: play of color, clarity, cut, and carat weight.
Opal displays background color in addition to Play-of-Color. Background color (also called bodycolor) is caused by the suspension of tiny impurities within opal’s silica spheres. These hues can range across the spectrum and may include one, two, or three colors, or all the colors of the rainbow. In general, connoisseurs prefer large, closely arranged patches of color over tiny, scattered dots. As with any play-of-color, no matter what the pattern, colors must be bright for the stone to be valuable. In addition to the arrangement and shape of the play-of-color patches, you should pay attention to “extinction”, or “dead spots,” when evaluating an opal. A dead spot is an area of the gem in which no play-of-color appears and only background color is visible. Dead spots detract from opal value, especially if there are several of them.
Clarity is the degree of transparency and freedom from inclusions. An opal’s clarity can range all the way from completely transparent to opaque. Experts prize different levels of clarity for different opal types. Inclusions and potch lines and are not to be confused with cracks. A crack line reflects light and greatly devalues an Opal.
An opal’s Cut will maximize its color, pattern, and clarity. Therefore, you will find that many exceptional opals might not be cut to standard sizes and shapes. Domed surfaces often give the best play-of-color.
Another important note: Buying opal in person is preferable to buying online. Why? Because opals are notoriously difficult to photograph, sellers may enhance their pictures to make a stone look better, often altering the opal’s true play of color. With an opal, you really should see it to believe it!
How to Care for Opal Jewelry
Opal hardness is variable depending on its exact composition and formation conditions, and ranges from 5 to 6.5 on the Mohs scale. Its toughness is very poor to fair, making opal a gem that is suitable for jewelry, but perhaps not for pieces that can receive heavy or frequent wear like bracelets and engagement rings (see our post on the 4 Most Popular Engagement Gemstones). High heat or sudden temperature changes can also cause opal to fracture. The only safe way to clean opal is with warm, soapy water. As always, remember that Bremer Jewelry will clean your opal jewelry safely for FREE!
What is tourmaline?
The name “tourmaline” comes from the Sinhalese words tura mali, which mean “stone of mixed colors.” As its name implies, tourmaline stands apart from other gems with its broad spectrum of colors in every shade of the rainbow. Tourmaline is not one mineral, but a fairly complex group of minerals with different chemical compositions and physical properties. Certain trace elements produce distinct colors,
Ancient magicians used black tourmaline as a talisman to protect against negative energy and evil forces. Today, many still believe that it can shield against radiation, pollutants, toxins and negative thoughts. Source: www.americangemsociety.com
Where is Tourmaline Found?
Tourmaline is mined in Brazil, Sri Lanka, Nigeria, Mozambique, Madagascar, Afghanistan, Pakistan and the U.S.—mainly Maine and California.
Somewhere in Brazil in the 1500s, a Spanish conquistador washed the dirt from a green tourmaline crystal and confused the vibrant gem with emerald. His confusion lived on until scientists recognized tourmaline as a distinct mineral species in the 1800s. People have probably used tourmaline as a gem for centuries, but until the development of modern mineralogy, they identified it as some other stone (ruby, sapphire, emerald, and so forth) based on its coloring.
One of the earliest reports of tourmaline in California was in 1892. In the late 1800s, tourmaline became known as an American gem through the efforts of Tiffany gemologist George F. Kunz. He wrote about the tourmaline deposits of Maine and California, and praised the stones they produced. Source: www.gia.edu
How to Buy Tourmaline
Tourmalines come in all shapes, sizes, color saturations and tones – from expensive electric blues to affordable olive greens. Regardless of the color, look for the following:
Color – Bright pure tones of red, blue and green are generally the most desirable but the vivid green to blue shades of copper-bearing tourmaline (in the trade this color is often referred to as Paraiba) are so exceptional that they are in a class by themselves. Since tourmaline colors can appear brighter in certain light, it is a good idea to examine it under a variety of light sources, to eliminate future surprises.
Clarity – Different varieties of tourmaline tend to have different clarities. Thus while large clean tourmalines in the blue and blue-green colors are available, almost all red and pink tourmalines will show eye-visible inclusions. The most common inclusions in tourmaline are fractures and liquid-filled healed fractures.
Cut – Due to its strong pleochroism, darker tourmalines are cut to display the lighter of the two pleochroic colors. Gems cut with this orientation are often rectangles and rectangular emerald cuts because of the elongated nature of tourmaline crystals.
Carat Weight – Fashioned tourmalines in larger sizes rise considerably in per-carat price. Even though specimens can reach spectacular sizes, these are rare. Availability drops and prices rise sharply for facet-quality rough material. For fashioned gems of similar color and clarity, the price per carat generally increases as the gems pass the five-carat milestone. Source: www.gia.edu
Need help choosing a tourmaline? No worries – Bremer’s own Certified Gemologist can help!
How to Care for Tourmaline Jewelry
Tourmaline ranks 7 to 7.5 on the Mohs scale. Its toughness is considered Fair. Tourmaline is generally stable to light and isn’t affected by exposure to chemicals, but heat can damage a tourmaline. High heat can alter the color, and sudden temperature change (thermal shock) can cause fracturing. For these reasons, we recommend warm, soapy water for cleaning tourmaline. The use of ultrasonic and steam cleaners is NOT recommended. If you’re worried about the proper cleaning of your tourmaline, keep in mind that Bremer Jewelry will clean it safely for FREE!