Jet has a few properties that make it useful and desirable. These have dictated its use across the centuries. The first of these properties is its ability to be easily carved or cut into shapes. Jet is soft and has a uniform texture, which allows it to be carved with precision.

Jet can be rubbed to a nice matte finish or polished to a very bright luster. Done well, these finishes enhance the aesthetic value of carved or cut pieces of jet.

Jet also has a low specific gravity. A strand of jet beads or a large cabochon thus weighs about 50% less than if they were made from agate, jasper, quartz, or other mineral material. This allows the beads to be worn with greater comfort and the brooch to be worn without placing as much stress or hanging awkwardly on the garment.

Physical Properties of Jet
Classification	Sedimentary rock similar to coal
Color	Black
Streak	Brown
Luster	Dull to matte to vitreous
Diaphaneity	Opaque
Cleavage	None, conchoidal to irregular fracture
Mohs Hardness	2.5 to 4
Specific Gravity	1.3 to 1.4
Diagnostic Properties	Low specific gravity, brown streak
Chemical Composition	Variable, but rich in carbon
Uses	Cut into faceted stones; carved into cameos, intaglios, bangles, rings, pins, combs, handles, and other practical or ornamental objects.