JET

Jet, mother of pearl and diamond pietra dura-style inlay bracelet

Species:  Jet
​​Mohs Hardness:  2.5 to 4 out of 10
Color:  Semi-translucent to opaque black to very dark brown
RI:  1.660 (+/- 0.020) (1.68 spot reading common)
Birefringence:  None
SR/DR/AGG:  SR
Pleochroism:  None
Spectrum:  Not diagnostic
Fluorescence:  Inert
SG:  1.32 (+/- 0.020)

Jet Facts

Jet is an organic black gemstone derived from coalified wood.

While it is related to coal, jet is much tougher and can be polished to a bright luster.

Jet is found in both hard and soft forms.  Hard jet is a result of carbon compression and saltwater, while soft jet is a result of carbon compression and freshwater.

"Whitby Jet" is a type of hard jet found in the Whitby area of England.  Whitby Jet was deposited in a saltwater swamp around 180 million years ago and has become famous for its better working qualities when compared to other types of jet.

Jet has been appreciated for thousands of years, having been unearthed from Neolithic French burials.

Jet experienced a surge in popularity during The Victorian Era.  After the death of Prince Albert in 1861, Queen Victoria went into mourning and began wearing all black, including her jewelry.  This black jewelry became known as mourning jewelry and often incorporated jet.

Jet beads saw a spike in popularity in the United States during the Art Déco Era.

Native Americans, especially the Zuni tribe, are known for incorporating jet into their traditional inlay jewelry.

Jet is often confused with other items such as onyx, glass, and plastic.

Fun Fact:  "French Jet" is actually not jet, and is a rather misleading nickname given to black glass used to imitate jet in Victorian Era mourning jewelry.

Jet Gallery

All photos courtesy of Scott Papper, GIA GG, AJP, CMA (NAJA)