Chalcedony is a broad gemstone family of many varieties of cryptocrystalline quartz gemstones. Chalcedony usually has a waxy luster and appears in a great variety of colors including blue, white, buff, tan, green, red, gray, black, yellow or brown. Different colored varieties of chalcedony have individual names including agate (banded), bloodstone (green with red spots), chrysoprase (apple green), carnelian (orange to red), flint (dull gray to black), jasper (spotted red, yellow, brown or green) and sard (light to dark brown).
Named for the Greek khalkos meaning "copper," and "pyrite," chalcopyrite is a major ore of copper. It has a metallic luster, resembling gold. Specimens are often collected and are found in Colorado, Arizona in the USA, as well as England, Tasmania, Germany, Canada, Spain, Japan and China.
Charoite offers an intriguing, mystical array of patterns that are both eye-catching and mesmerizing. The patterns often exhibit a combination of swirls, veins and spots that give each piece a unique and magical appearance. The name Charoite is used to describe both a mineral and an attractive gem material primarily composed of charoite. The gem material comes from the remote, mountainous region of the Sakha Republic of Russia, which remains its only known source.
Chondrodite, named for the Greek word for grain, "chondros," is a member of the humite group of minerals. Its gemmy hues range from red to yellow to orange, with the latter resembling the color of spessartite garnet. It can be found in several places including New York, Burma, Tanzania, and Afghanistan.
Chrome diopside has several origins, but most of the finest material, and the only commercially viable deposit, is in the Republic of Sakha in Siberia, Russia. As you can imagine, production of this Siberian treasure is sporadic due to extreme winters that last more than eight months. The vivid greens of chrome diopside are a welcome alternative to rare and pricey emerald or tsavorite garnet, but it has yet to gain mainstream recognition due to its limited availability. Minor sources of chrome diopside include Australia, Austria, Canada, Finland, Italy, Madagascar, South Africa, and the United States.
First discovered in Tanzania in the 1960's, chrome tourmaline is a fairly new addition to the vast tourmaline family. A true collector's gem, chrome tourmaline exhibits bright green color that resembles, and even rivals, that of the finest emeralds. While it is a type of green tourmaline, not all green tourmalines contain chromium and can be called chrome tourmaline. True chrome tourmaline is more highly prized, as it is a more rare occurrence for chromium to be a coloring agent, which often results in a much brighter and richer green color.
Chrysoberyl is the name of a mineral as well as three different gem varieties two of which are widely accepted as some of the most rare and valuable of all phenomenal gems. The gem commonly known as chrysoberyl is a yellowish-green, brownish-yellow, or colorless transparent to translucent mineral that is usually faceted into gems and generally considered a collector's stone. While not often set in jewelry, its characteristics make it ideal for such use. When chrysoberyl displays color-change properties, it is known as alexandrite, and when it exhibits chatoyancy, it is known as cat's eye chrysoberyl.
Chrysocolla, derived from the Greek chrysos meaning "gold," is a copper mineral. Crystals are very rarely seen, but it is frequently intergrown with other minerals such as quartz or opal. This results in a harder, more resilient gemstone, as pure chrysocolla is soft and fragile. Its copper content is responsible for chrysocolla's range of bright green to blue hues.
One of the most coveted varieties of chalcedony quartz, chrysoprase is prized for its apple green color and rarity. Chrysoprase's name comes from the Greek words chrysos meaning “gold,” and prason meaning “leek,” due to its color similarities with the vegetable.
Named from Arabic and Persian words for "dragon's blood," cinnabar comes in a remarkable brick-red color and has been used as a pigment in China as far back as prehistoric times. Gem crystals are rare collector's pieces, but opaque material is often cut into cabochons. Natural cinnabar is a major mercury ore and is not used in jewelry making, but a resin product that closely resembles it, is used in jewelry. The red color is so fresh and vibrant that, in China, many people call it "China Red."
Citrine is one of the most popular gemstones in the quartz group. Prized for its excellent transparency, citrine is one of November's birthstones. Naturally, it occurs in close proximity to amethyst and is found in beautiful golden, mandarin orange and madeira red hues. It's possible that quartz crystals that grew naturally as amethyst or smoky quartz were turned into citrine by natural heat from nearby magma activity. Today, many of the citrines on the market are actually heated amethyst or smoky quartz.
A relatively new addition to the world of gems, clinohumite was first discovered in 1876 within stones erupted from Mount Vesuvius. Only recently have gem-quality pieces been found in locales including Tajikistan's Pamir Mountains. Clinohumite's coloring typically ranges from bright yellow to deep orange to red, but a few brown specimens have been found.
Named for its resemblance to zoisite, clinozoisite is a colorless to pale grayish-yellow to green-colored mineral ideal for faceting. This gem was first discovered in Austria 1896, but there are many locations world wide where specimens have been found.
Cloisonné is an enameling or inlay technique used to decorate jewelry or other metallic objects. The enamel or gemstones are applied to create patterns or geometric designs. The colored material is placed in compartments or in between raised strips of metal. The earliest examples of the technique can be found in Egypt, Mycenae, and Mesopotamia and date to around 1200 to 1101 BC. Cloisonné has been used as a decorative technique by many cultures around the globe.
Cobaltocalcite refers to a stunning pink-red to slightly purplish-red cobalt-rich calcite mineral. Another name for this stone is cobaltoan calcite. Crystals often form as drusy masses and when faceted, gems are rarely seen in sizes greater than 2 carats.
A major source of boron, colemanite was discovered in 1884 and named for the owner of the California mine where it was first found, William Tell Coleman. The color of this stone ranges from colorless to white to grey, sometimes yellowish. Specimens are very sensitive to heat. The short, prismatic crystals are often sought after by collectors. Colemanite is rarely seen in the form of gemstones as it presents a challenge to lapidaries because crystals are soft, brittle and have perfect cleavage.
A conch is a marine gastropod or, more simply, a large sea snail. Conchs are valued for their meat, shell, and non-nacreous pearls. Conch pearls are formed by concentric layers of fibrous calcium. This layering often produces a much-desired flame structure, which is characteristic of conch pearls. Because they are a calcareous concretion, the pearls have a porcelain finish and luster, very similar to the interior of the conch shell. Conch pearls are usually found as a by-product as fishermen clean their catch for conch meat. The gems are usually baroque or oval and generally a salmon-colored orange pink.
Copal can be thought of as 'baby amber.' Like its much older counterpart, it is a hardened resin that originated as tree sap. Copal is similar in both appearance and chemistry to amber. Opinions vary from source to source as to when copal becomes amber, but the general consensus is that organic resin younger than 10 million years old is copal, while anything older is amber. As amber can be as old as 360 million years old, copal is substantially younger.
Many minerals are copper ores, meaning they contain copper that could actually be extracted. Copper weathering is often involved in the unique coloration of specimens. Popular minerals that fall in this category include azurite, malachite and chrysocolla.