cat's eye

Cat's eye chrysoberyl displays a chatoyant, cat's eye effect
Photo courtesy of JTV
Variety:  Cat's Eye
Species:  Chrysoberyl
Mohs Hardness:  8.5 out of 10
Color:  Yellow to yellowish green, grayish green, brown to brownish yellow, with chatoyancy
RI:  1.746 to 1.755 (+0.004 / -0.006) (1.75 spot reading common)
Birefringence:  0.008 to 0.010
SR/DR/AGG:  DR (AGG reaction possible)
Optic Character:  Biaxial positive
Pleochroism:  Light to medium tones of the gem's bodycolor in semi-transparent stones
Spectrum:  Strong band at 444nm
Fluorescence:  Usually inert
SG:  3.73 (+/- 0.02)
Routine Treatments:  None
Additional Enhancements:  Dyeing

cat's eye facts

Cat's eye chrysoberyl
Photo courtesy of JTV

Cat's eye chrysoberyl possesses a rare phenomena known as chatoyancy.

Cat's eye occurs in many different colors and is identified by its narrow slit that resembles a feline's pupils.

The cat's eye effect is due to many parallel, fibrous needle inclusions that scatter and reflect light back in a thin band.

​Although several different gems can display a cat's eye effect, cat's eye chrysoberyl is the only gem that can be referred to as simply "cat's eye" without a modifier.