BLACK ONYX AND OTHER FORMS OF CHALECEDONY ESTATE JEWELRY AND ANTIQUE JEWELRY

ORIGIN OF NAME
The term chalcedony may derive from the ancient Greek port Chalcedon. Carnelian is derived form the Latin word meaning "cornelian cherry". Chrysoprase is derived from the Greek words "chrysos" and "prase", which combined mean "golden leak".

VIEW OUR BLACK ONYX ESTATE JEWELRY AND VINTAGE JEWELRY COLLECTION
Art Deco Black Onyx and Diamond 14KT Gold Estate Ring
Estate Ring Big Vintage Onyx and Diamond Art Deco 14KT
Antique Diamond Onyx Fly Brooch
Black Onyx Mabe Pearl Ring
Estate Black Onyx and Diamond Ring 14kt Gold
Chalcedony Diamond Filigree Ring

HISTORY
Agate has been found to have been used during the stone age (20,000BC to 16,000BC). Agate, carnelian and chrysoprase were used by the Egyptians before 3000 BC. Carnelian was often used by the Romans to make cameos. The prophet Mohammed even wore a carnelian seal. During Roman empire, Idar and Oberstein provided agate and jasper. These German towns are no longer a source of chalcedony, but remain known for their skills with processing the stones.

Chalcedony is a common stone. It is formed in cavities, cracks and is formed where silica-rich waters percolate through sediments and rocks - especially where there is volcanic origin.

ESTATE JEWELRY AND ANTIQUE JEWELRY USAGE
During the Early Victorian Period, chalcedony was often used to make cameos from jasper and agate. Bloodstone was also used in the Victorian Period. During the late Victorian Period, onyx was used for making rings. During the Art Deco Jewelry Period, black onyx, chrysoprase and cornelian agate were widely used materials.

LEGENDS
Bloodstone was believed to preserve the owner's health and protect them against deception. Chrysoprase was believed to strengthen vision and relieve internal pain. Carnelian was believed in the thirteenth century to give the owner courage for battle. In Volmar's thirteenth-century novel, Steinbuch, created the legend that a thief may escape his execution by putting chalcedony in his mouth.

With a hardness of 7.5, on the Moh's Scale, chalcedony is hard enough for daily wear. Exposure to cleansing agents, even mild soaps, can ruin a chalcedony's finish. Rings should always be removed prior to washing one's hands. Likewise, ultra-sonic cleanings can remove the finish and ruin the stone.

SOME VARIETIES OF CHALCEDONY:

AGATE: Applied to chalcedony that is translucent or semi-translucent. Chalcedony is more specifically seen with curved or angular bands. Often colorless versions are dyed red, green, black yellow or blue. Agate is mainly found in Mexico, Brazil, Namibia, Madagascar, Russia and India.

BLOODSTONE: An opaque chalcedony that is usually dark green, almost black. It is distinguished by its orange or red spots. It was once used for medicinal purposes to stop bleeding. The main source for bloodstone is India. Bloodstone was often used in early Victorian jewelry.

CARNELIAN AGATE: Clear orange or red chalcedony. Most all is heat treated. Found in South Africa, China, Brazil, Morocco, and Uruguay.

CHALCEDONY: White, gray or light gray stone.

BLUE CHALCODONY: Blue stone generally from Namibia.

CHRYSOPRASE: Pale to medium green stone, looks like jade. Found in Australia, Zimbabwe, Brazil, Poland and Kazakhstan. The most rare and valuable variety.

JASPER: An opaque, fine-grained stone. Jasper is distinguished from other forms of chalcedony by the fine sugar-like grains it has. Normally it is multi-colored by foreign materials. It is usually spotted or striped. Most common colors are yellow, green, brown or gray. Jasper is found worldwide. Found often in Venezuela, Germany and Russia.

ONYX: Parallel bands that are black and white, which is rare. Black onyx is usually a dyed chalcedony.

TECHNICAL DATA
Crystal system: Trigonal
Cleavage: None
Refractive Index 1.53 - 1.54
Specific Gravity: 2.58 - 2.64, some jasper 2.9

MOH's SCALE
The measure of relative hardness, Moh's Scale defines common stones and minerals for the hardness and durability. Hardness is one measure of the strength of the mineral relative to its chemical bonds. It is not the same as brittleness, which is related to the structure of the mineral. Hardness is tested by scratching. Using Moh's Scale, the higher the number, the harder the mineral. talc (used to write on chalkboards) is defined as the softest mineral and is given the value of 1. Diamonds are the hardest and are given the value of 10.

Moh's Scale is as follows:
1. Talc
2. Gypsum
3. Calcite
4. Fluorite
5. Apatite
window glass or a typical knife blade
6. Orthoclase
6.5 - 7 chalcedony
a good steel knife
7. Quartz (amethyst and citrine)
8. Topaz
9. Corundum (rubies and sapphires)
10. Diamond

SPECIFIC GRAVITY
The specific gravity is the ration of the density of an object when compared to water. In the simplest testing, it is simply the weight of a mineral compared to its volume. The volume of the stone is measured by the amount of water in displaces.

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