Lilac to violet variation of crystalline quartz

Physical properties:

Chemistry: SiO2
Hardness: 7
SG: 2.65-2.66
Cleavage: None
Fracture: Conchoidal, moderately brittle
Heat sensitivity: None

Optical properties:

RI: 1.54-1.55
Dispersion: 0.013 (moderate)
Double refraction: 0.009 (weak)
Pleochroism: Weak to distinct, purple and reddish-lilac
Critical angle: 40°

Facet angles (pavilion/crown):

Vargas: 43°/42°
Olson: 43°/42°
Soukup: 43°/42°
Roth: 43°/42°
MDR: 43°/42°
Schlagel: 42°/38°
Hashnu: 43°/42°
Sinkankas: 43°/40-50°
GIA: 43°/42°
Perkins: 43°/42°
Raytech: 43°/42°
Cornwall: 44°/36°
Weikoff: 43°/42°
Carroll: 43°/35.3°

Cutting lap:

All grit sizes

Facet polishing:

Vargas: Cerium oxide on acrylic, Aluminum oxide on tin or tin/lead
Olson: Tin or cerium oxide on acrylic or tin, Ultralap
Christiansen: Cerium oxide on acrylic, Aluminum oxide on tin or tin/lead
Raytech: Aluminum or tin oxide on Fast Lap, tin or phenolic
MDR: Tin or cerium oxide on acrylic or tin

Cabochon polishing:

Olson: Tin or cerium oxide on felt
Christiansen: Aluminum, tin, or cerium oxide on felt/leather
Cox: Cerium oxide on felt/leather
Covington: Cerium oxide on felt/leather


According to color banding and with color centers in the culet.


There is plenty of synthetic amethyst available on the market.


Sometimes difficult to polish on plexiglass (acrylic, lucite); try using aluminum oxide on tin lap or LightningLap A1.

LightningLap with cerium oxide is excellent for polishing large facets.

Amethyst rough

Amethyst on Gemdat

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