Gemstone Glossary

Quartz

Quartz is generally divided into two groups: the transparent crystalline varieties and the translucent to opaque chalcedonies that are microcrystalline forms of quartz. There are many different varieties in these two types but they have one thing in common: they are low in cost. Some are downright cheap! Quartz is one of the most abundant minerals in the earth's crust. It is also one of the most interesting.

Amethyst is the queen of the quartz varieties and in better qualities it is the most expensive of the quartzes. Amethyst ranges from pale to dark violet. The finest qualities of Amethyst are a medium dark violet with a strong secondary red color. Darker shades of Amethyst may appear slightly differently under different light sources.

Amethyst of all qualities is available in all sizes and shapes. Light Amethyst will be very low in per carat prices with the finest qualities still well under US$l00 per carat. Darker Amethyst of any size will have color zoning. This may not be visible without extensive examination. Often the zoning consists of areas of red violet and areas of blue violet, this combination can enrich the appearance of the stone. Sometimes the zoning is easily visible and detracts from the beauty of the stone. If the zoning is unsightly the value is lessened.


Ametrine is a bi-color variety that is part Amethyst colored and part Citrine colored. It was first discovered in Bolivia. Generally Ametrine is cut into octagon or emerald cut shapes to emphasize the two colors. Ametrine has been carved into some very interesting gem art works. Prices will start in the low end and go to moderate price per carat for exceptional pieces.

Smoky Quartz is brown transparent quartz of all shades; it generally has a slightly grayish cast. It is much easier to find Smoky Quartz in large sizes; it is not always economically feasible to cut it into small sizes. Prices should always be very inexpensive.

Colorless Quartz (also called "rock crystal") simply lacks interest as a jewelry stone. Even when it is well cut it lacks brilliance. Occasionally it will contain some interesting inclusions that can increase its appeal. Colorless quartz is occasionally found with rutile needles inside which look like long golden threads, sometimes arranged in a pattern. This is called "Rutilated Quartz" and is popular in art jewelry. Black Tourmaline crystals can also create a pattern inside colorless quartz for a unique appearing gemstone. Other mineral inclusions are possible. In rare cases, quartz will contain gold. Most gold bearing quartz is milky white rather than transparent. These included quartz materials are being used for carvings and can be gemstone art works.

Beads made from quartz have been popular for a hundred or so years; these are often faceted into appealing shapes. Again these items are low in price. If a gem is carved into an "art work" the quality of the work may be what you are paying for rather than the raw material; these items will have to be valued accordingly.

Tiger's eye is quartz with asbestos inclusions; this gives it a subtle silky appearance. Generally it is golden to brown in color; it can also be dyed. Blue material is called Crocidolite. Quartz also comes in cat's-eye form; it is usually a golden yellow.

Star quartz is a fascinating stone; the quartz may be colorless or pink. The stars are six-rayed and roll around the stone as it is moved. Sometimes Star Quartz is cut into spheres which are really fun.