Articles

United States Faceting Guilds, Clubs and Schools

Big Sky Faceters Guild, Inc. Affiliation: Newsletter: Mailing Address: PO Box 564, Great Falls, MT 59403-0564 Meetings: 4th Tues. 7:00pm, Montana School for Deaf & Blind E-mail: Phone: (406) 727-2315 Columbia-Willamette Faceter’s Guild Faceters Guild of Southern California Affiliation: California Federation of Mineralogical Societies Newsletter: Angles Mailing Address: PO Box 5433 Buena Park, CA 90622 […]

Properties of Commonly Faceted Minerals and Materials

Material Refractive Index Critical Angle Birefringenge Dispersion Hardness Specific Gravity Crystal System Class Formula Cleavage Apatite series 1.64 37.57° .004 .013 5.0 3.05-3.20 hexagonal 6/m Ca5(PO4,CO3)3(F,Cl,OH) 2; {0001}indistinct; {10-10} trace Beryl 1.57-1.60 38.68-39.56° .006-.009 .014 7.5-8.0 2.60-2.90 hexagonal 6/m 2/m 2/m Be3Al2Si6O18 1; {0001} indistinct Color varieties of beryl include aquamarine (blue), emerald (green), goshenite […]

Design Principles

by Fred Van Sant General Considerations: First we should get out of the way those factors which do affect OP (optical performance) but are not inherent in the design itself. Mainly they have to do with the matching up of the design with your particular piece of rough and/or the changing of the sets of […]