First off, Topaz is harder than Quartz. Topaz has a Mohs hardness rating of 8, and Quartz is a 7. There are a variety of colors of quartz, known by their common gemstone names, as follows:
- Rock Crystal - or clear crystal quartz; can have inclusions, such as rutile or tourmaline; the most common type of quartz
- Smoky Quartz - dark brown to grey to black; frequently included with rutile needles
- Amethyst - purple, deep to light, violet; the most valuable of all quartz gems.
- Ametrine - contains both amethyst (purple) and citrine (golden yellow)
- Citrine - light yellow to deep golden brown; most citrine is heated amethyst. If heated, has a reddish tint.
- Lemon Quartz - sparkling golden "margarita" color, natural. One of the very few genuine "fruity" quartz stones.
- Prasiolite - leek green; NOT natural, always heated amethyst or light yellow quartz
- Rose Quartz - light pink to strong pink; cloudy
- Aventurine - green; red-brown; golden-brown; sparkling inclusions. Green often sold as "jade"
- Blue Quartz - turbid (cloudy) blue; never clear. Caused by crocidolite fibers
- Tigers Eye - brown with gold "ray of light" on surface
- Hawk's Eye, Cat's Eye - White, gray, green, yellow, brown Cat's Eye; blue-grey to blue-green in Hawk's Eye; like Tiger's Eye, caused by reflection of light by parallel fibers, needles, or channels.
- Chalcedony - translucent quartz in blue,white, grey; bloodstone (dark green with red spots)
- Agate - many colors included banded, onyx
- Carnelian - red to orange to brown translucent stone
- Chrysoprase - rich green, very often used to misrepresent jade
- Chrysocolla Chalcedony, marketed as "Gem Silica": relatively rare, blue to blue-green, opaque to near transparent material; the most expensive type of chalcedony.
I read a handy tip to tell if a stone is Topaz or not:
- Clean the stone and dry it.
- Using a rod or something small, place a drop of water on the surface of the stone.
- If it's Topaz, or a stone that is harder than an 8 on the Mohs scale, the drop will just sit there.
- If it's Quartz, or anything softer than an 8, the drop of water will disperse over the stone.
- The harder the stone, the more rounded the drop of water!
|So-Called "Tanzanite Blue Quartz"|
|Blue Quartz with Tourmaline|
Blue Quartz varies in color from grey to deep blue, like navy blue. Natural blue quartz is always colored by inclusions of other minerals. Here (above right) is a picture of a double terminated quartz from Brazil. It is deeply colored blue by inclusions of fine needles of indigolite, a blue tourmaline. From the Jenipapo Mine, Itanga, Minas Gerais, Brazil.
Chalcedony is a natural blue quartz. Chalcedony blue quartz is milky, cloudy, not crystal clear.
But what is the crystal clear "Blue Quartz" that is found in strands of faceted briolettes, or all kinds of jewelry? Sometimes sellers call it "London Blue Quartz" or "Sky Blue Quartz" which are actually names of TOPAZ gemstones, not quartz. Another example of "creative marketing" on the part of sellers, or vendors who supply sellers. Actually, these are not gemstones at all----these are glass, sometimes called "Fused quartz". The rough can be purchased with names such as "Blue Sapphire", "Cornflower Blue", "Electric Blue Topaz", "Cobalt", and more. These can be seen HERE. These have a Mohs rating of about 5 to 6.5, the same as window glass.
Hydrothermal quartz is synthetic quartz that is grown in a lab. According to syntheticgems.org it has a Mohs rating of 7. I have contacted some manufacturers of hydrothermal quartz, and I haven't found anyone who makes this for jewelry---it is strictly for industrial applications (grown for quartz watches, electronics, etc.). So I'm not sure if I quite believe that so-called "hydrothermal quartz" exists in the jewelry world because I haven't found any proof of that. I do know that "hydroquartz" is absolutely GLASS though, just like "fused Quartz" as I mentioned already.
|"Mystic" Blue Quartz|
Personally, I wouldn't buy any sort of "blue quartz" that is crystal clear. I assume that it is glass. I have no reason to think otherwise. In the picture of the "Tanzanite Quartz" above, you can see tiny bubbles---a sure sign of glass. One of the largest (if not THE largest) supplier of this "hydro blue quartz" is Alibaba in China, and we all know that they sell a lot of fakes and glass gems. If I want a beautiful blue gem, I will buy Topaz or my favorite, Aquamarine. These are real for sure! And they have a value!
So, buyer beware!