Apatite
Last updated: April 2026
Neon blue-green apatite from Madagascar is often confused with paraiba tourmaline or aquamarine. Hardness is exactly Mohs 5 — a knife blade or steel file will scratch it. Yellow apatite shows strong yellow-orange LW fluorescence.
Apatite has a specific gravity of 3.20 and a refractive index of 1.628–1.649, with a Mohs hardness of 5. It is uniaxial −.
Physical & Optical Properties
Key Differentiators
- Hardness exactly 5.0 (Mohs reference mineral) — scratched by a knife or steel file
- Uniaxial negative
- RI 1.628–1.649 — higher than aquamarine (1.577–1.583)
- SG 3.17–3.23 — heavier than aquamarine (2.68–2.80)
- Yellow apatite: strong yellow-orange LW fluorescence (diagnostic)
Natural vs. Synthetic
Synthetic apatite is commercially available (Czochralski (rare laser-grade; not commercially sold as gems)). Distinguishing natural from synthetic typically requires microscopic examination of internal features.
- General Note: No commercial synthetic apatite for gemstone use. All is natural. Synthetic: Glass imitations are isotropic SR, have different RI, no fluorescence match.
GemID Pro includes a two-phase natural vs. synthetic testing protocol for Apatite.
Start Free TrialTreatments
- Heat Treatment (blue apatite)
- Irradiation (produces unstable neon blue)
Price Context
Price context is approximate. GemID is not an appraisal tool. Results are indicators, not certified valuations.
Related Comparisons
Measurement Guides
Identifying an apatite? GemID walks through these tests in order — RI, SG, fluorescence, and more.
Try GemID Free →Studying for the GIA, FGA, or FEEG practical? Apatite is one of the 130 species in GemID’s drill and exam pool — practice identifying it from its measured properties under timed exam conditions.
Practice exams →