Mali
Mali is a grossular garnet mixed with some andradite. The more andradite, the higher the optical values, but also usually a browner and less attractive color. Cut stones with high purity and size over 2 ct are rarities that command large sums.
Physical properties:
| Chemistry: | Ca3(Al,Fe)2(SiO4)3 |
| Hardness: | 7.25 |
| SG: | 3.64–3.67 |
| Cleavage: | None |
| Fracture: | Sometimes slightly brittle |
| Heat sensitivity: | None |
Optical properties:
| RI: | 1.74–1.78 |
| Dispersion: | Approx. 0.04 (high), Grossular 0.027 – Andradite 0.057 |
| Birefringence: | None |
| Pleochroism: | None |
| Critical angle: | 34.5° |
Facet angles (pavilion/crown):
| Vargas: | 41°/40° |
| Olson: | 39°/37° |
| Soukup: | 42°/37° |
| Roth: | 42°/37° |
| MDR: | 42°/37° |
| Schlagel: | 40°/36° |
| Hashnu: | 41°/39° |
| Sinkankas: | 40°/40° |
| GIA: | 42°/37° |
| Raytech: | 40°/38° |
Cutting lap:
Medium-fine
Facet polishing:
| Vargas: | Aluminum oxide on tin/lead, tin oxide on tin |
| Olson: | Chrome oxide on tin |
| Soukup: | Aluminum oxide on tin or tin/lead |
| Christiansen: | Aluminum oxide on tin/lead, tin oxide on tin |
| MDR: | Tin or aluminum oxide on tin, aluminum oxide on type metal |
Cabochon polishing:
| Olson: | Chrome oxide on leather |
| Christiansen: | Aluminum, tin, or chrome oxide on leather or wood |
| Cox: | Aluminum or chrome oxide on leather, cerium oxide on felt |
| Covington: | Chrome or cerium oxide on felt |
Orientation:
For best yield
Treatments/synthesis:
None
Tips!
Mali is often too brittle for coarse or new cutting lap. High RI and dispersion effectively mask smaller inclusions.
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