Gem Reference

Colourless apatite is a scarce, low-value collector stone whose constants (RI 1.63, uniaxial negative, SG 3.2) make it a favourite identification exercise.
Sign in to unlock price ranges by tier, common misidentifications, diagnostic inclusions, treatments, spectra, trade names and sources — free with the GT200 Gem Identification course.
GT200 Gem Identification ↗ Sign inBrowse the free gem reference · Test your eye — the Great Gem Quiz · Singapore gem testing labs