Gemstone Spotlight: Chalcedony

by: Ben Tseytlin - on Antiques & Jewelry

The gemstone known as chalcedony is a member of the quartz family. It comes in a variety of patterns, colors and shapes, and is distinctive due to its translucency combined with its solid and light color which usually ranges from blue to gray or white.


Chalcedony has a rank of 7 within Mohs scale, and is average in terms of hardness. The stone is famous for its ability to polish, and exhibits a spectacular glow that appears to originate from within. Although it is not nearly as famous as diamonds, rubies or emeralds, it is one of the most important gems in the world due to its industrial and scientific uses.

Chalcedony quartz is distinct from other stones due to its composition (which is largely silicon dioxide), along with its crystalline hexagonal structure. It is a dense variant of silica, which results in crystallization that is exceptionally fine, so much so that some of its parts are not visible even with a microscope. Chalcedony is also comprised of morganite, which is a silicate mineral that functions as a quartz polymorph. This gem is also piezoelectric, which means that it can carry miniature electrical charges.

This gem can usually be found in environments which are either volcanic or sedimentary and like other stones its formation occurs over a long period of time. Some sites provide higher quality chalcedony than others, but the stone is widely distributed, being found in places ranging from the United States to Brazil, South Africa, India, Uruguay and even Madagascar.

How To Shop For Chalcedony

When shopping for chalcedony you want specimens that are translucent, as these are most desirable. The gem often appears milky, which is a sign that it is authentic. As long as its translucency is intact, the milky clarity won’t affect its value much. The stone sometimes has inclusions which are visible but in many cases they are acceptable as they do not erode its beautiful appearance. Most jewelers will cut chalcedony in a cabochon style, as it accentuates the gem’s glow. Other shapes it can be cut in include ovals and trillions. This particular stone is excellent for carvings, seals, and any form of ornamentation.

How To Wear And Care For Chalcedony

Chalcedony was known to the ancients and was celebrated by them. The most expensive form of Chalcedony is Chrysoprase, which is apple green in color and exceptionally rare. These particular specimens can command prices comparable to diamonds or sapphires and are frequently set into jewelry that is high end. Chalcedony can be worn in the form of necklaces, rings and pendants. It is highly resistant to wear and can be worn with urban, classy or tribal clothing.

This gem is very low in maintenance and is very versatile, capable of being worn by men or women. When purchasing Chalcedony select it based on size and not its carat weight. The stone should be cleaned using water which is warm and soapy and it should never be cleaned with chemicals or stored near other gems as it could be scratched by them.