Synthetic Moissanite

1. Chemical Composition Silicon Carbide - SiC
2. Classification / Type This is a man made material. The term synthetic is used since it has a natural counterpart as inclusions seen in diamonds and other gemstones.
3. Colors / Varieties All colors but colorless and light yellow are common.
4. Crystal System Hexagonal
5. Hardness 9.5
6. Specific Gravity 3.22
7. Cleavage / Fracture Indistinct / Conchoidal fracture
8. Optic Character Anisotropic, D.R.; Uniaxial Positive
9. Lustre Adamantine
10. Refractive Index / Birefringence 2.648 - 2.691 / 0.043
11. Pleochroism Weak
12. Dispersion 0.105 (high fire)
13. Magnification Strong doubling of facet edges, inclusions and culet (generally seen through kite facet), reflective needles.
14. U.V. Fluorescence Inert
15. Cause of Color -
16. Spectrum Not characteristic
17. Treatment (Enhancement) -
18. Specific Tests & Remarks Moissanite probes are available which are defined for synthetic moissanite values of thermal conduction such as moissanite thermal probe.
19. Synthesis Large crystals are grown by sublimation from a feed powder, diffusion through graphite and growth directly from the vapor phase on a seed crystal. In the sublimation process, the silicon carbide vaporizes and recrystallises without passing through the liquid stage.
20. Simulants (with key separation tests) G.G.G. (dispersion, doubling, S.G.), Y.A.G. (dispersion, doubling, S.G.), Synthetic Cubic Zirconia (S.G., dispersion, doubling), Diamond (dispersion, doubling, inclusions, S.G.), Strontium Titanate (dispersion, doubling, S.G.), Sphene (dispersion, inclusions), Synthetic Rutile (S.G., dispersion), etc.
21. Geological Occurrence In a laboratory.
22. Sources -
23. Cuts & Uses Facetted cuts.