IOLITE

Iolite and amethyst cross pendant

Species:  Iolite
​​Mohs Hardness:  7 to 7.5 out of 10
Color:  Violet through slightly violetish blue, with strong eye-visible pleochroism.  Small stones appear grayish.
RI:  1.542 to 1.551 (+0.045 / -0.011)
Birefringence:  0.008 to 0.012
SR/DR/AGG:  DR
Clarity Type:  Type II
Optic Character:  Biaxial negative
Fluorescence:  Inert
SG:  2.61 (+/-0.05)
Routine Treatments:  None

Iolite Facts

​Iolite is strongly pleochroic.  You'll see 3 distinct colors in 3 different crystal directions.

Iolite is one of the few gemstones that is not typically treated in any way.

Iolite is the 21st wedding anniversary gemstone.

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