Gem Library

BUYER’S OVERVIEW:
Jet is considered to be a semi-precious gemstone even though it is not a mineral. Organic in origin, Jet was formed by the decomposition of ancient trees called Protophinacea (similar to modern day Cypress) under high pressure over millions of years underground. While its availability is limited, good size, clean, natural stones are available. Jet ranges in color from a very dark brown to black, takes a good polish and has been found in jewelry dating back to 17,000 BC in Asturias, Spain.

COLOR:
Jet is found in a very narrow color range from dark brown to black.

APPEARANCE:
Semi translucent to opaque.

SIZE RANGE:
1 – 20 carats, pieces over 1000 carats are known.

TYPICAL CUTTING STYLES:
Semi translucent to opaque: beads, carvings, cabochons, buttons and faceted.

POSSIBLE ENHANCEMENTS & TREATMENTS:
Jet has no known enhancements.

HARDNESS:
2½ to 4 on the Mohs scale.

BEST USE OF THE GEMSTONE:
Jet is not a strong gemstone and as such, gemstone earrings, pendants, pins, and tie tacks are probably the safest choice for this stone. Rings should be limited to occasional wear and the stones should be set with a protective setting. Avoid rough handing.

CARE & CLEANING:
It is best to never expose colored gemstones to cleaning solvents or chemicals of any kind.
Common cleaning methods include:
Ultrasonic: never
Steamer: never
Warm soapy water: safe
Reaction to Chemicals: acid may dull the surface
Reaction to Heat: burns easily with a coal like or oily odor.
Stability to Light: generally stable after prolonged exposure to sunlight or UV light.

INTERESTING FACTS ABOUT THIS GEMSTONE:
The English noun “jet” derives from the French word for the same material “jaiet”. Jet is either black or dark brown and unfortunately for this wonderful gemstone, the color name “jet black” is better known than the substance from which the descriptive phrase was derived. Until recently it was thought that Jet came from a species of ancient trees called “Araucaria” but it has now been determined that Jet comes from a tree called “Protophinacea”, similar to modern day Cypress. Jet is found in two forms, hard and soft, with the hard form resulting from the compression of carbon with salt or sea water, and the soft form from the compression of carbon and fresh water. Jet attained its peak fame during the reign of Queen Victoria when she wore Jet as part of her mourning dress. Long necklaces of Jet beads were very popular with flappers during the Roaring Twenties.

DESIGNATION:
This gem has a long history but has no traditions currently associated with it.

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