Yttrium Aluminium Garnet (Y.A.G.)

1. Chemical Composition Yttrium Aluminium Oxide - Y3Al15O12
2. Classification / Type Y.A.G. is a man made material with a garnet internal structure. The term synthetic is not used to refer to this material since it does not have a natural counterpart.
3. Colors / Varieties Colorless, blue, green, yellow, lilac, pink.
4. Crystal System Cubic System
5. Hardness 8.5
6. Specific Gravity 4.55 - 4.60; may vary with dopants used.
7. Cleavage / Fracture None / Conchoidal fracture
8. Optic Character Isotropic (S.R.)
9. Lustre Adamantine to vitreous.
10. Refractive Index / Birefringence 1.833
11. Pleochroism Nil
12. Dispersion 0.028
13. Magnification Gas bubbles aligned in fingerprints, twisted droplets, and stringers.
14. U.V. Fluorescence Varies with dopants used.
15. Cause of Color
  • Green: Chromium
  • Blue: Cobalt
  • Purple: Neodymium
  • Red / Pink: Manganese
16. Spectrum Varies with dopants used.
17. Treatment (Enhancement) -
18. Specific Tests & Remarks Strong see-through effect.
19. Synthesis Czochralski method.
20. Simulants (with key separation tests) G.G.G. (S.G.), Synthetic Cubic Zirconia (S.G., dispersion), Zircon (spectrum, optic character, doubling), Sphene (optic character, doubling, dispersion), Strontium Titanate (dispersion, S.G.), Synthetic Rutile (optic character, dispersion), Diamond (dispersion, inclusions, S.G.), Demantoid (inclusions, spectrum, S.G.), Spessartite Garnet (spectrum, inclusions, S.G.), etc.
21. Geological Occurrence In a laboratory. No natural counterpart.
22. Sources -
23. Cuts & Uses Facetted cuts, beads, etc.