Faceting Tips for Exotic Gemstones

Answer: Check out Faceting for Amateurs by Glenn and Martha Vargas. This book features an appendix that lists most gem materials and includes cutting and polishing information. It also has a section on unusual faceting materials.

Notes on Faceting Selected Exotic Gemstones

Here's a summary of special notes for your exotic gemstones.

• Actinolite has very easy cleavage in two directions and requires care. Sharp corners will fray.
• Amblygonite has perfect cleavage in two directions.
• Celestite should be kept away from sulfite compounds. It's extremely heat sensitive and best cut as a round gem.
• Dioptase is brittle.  Its cleavage may mean trouble on course laps. Use only extra or ultra-fine laps. Use speed of 100 rpm or less for polish.
• Epidote is easy to cut and polish, but its cleavage may separate during heating. If the rough is a twin, the twinning planes can present problems.
• Leucite should pose no special problems if cut on fine laps at slow speeds. Keep it wet during polishing.
• Smithsonite should pose no problems if you avoid the three cleavage planes. Dopping heat with care.

Don't forget that the International Gem Society (IGS) reference library includes a Gemstone Encyclopedia. This resource includes all kinds of information on lesser known gemstones and collector items.

Roland B.