Art Kavan’s Facetron Installation
by Art Kavan, Old Pueblo Lapidary Club Here is a brief summery of my experience with the ohm meter & dial indicator, plus a few pictures to give an idea of how I implemented them on my Facetron. From the explanation of how well the ohm meter was supposed to perform I thought that it […]
History of the International Challenge Cup Competition
by Glenn Klein On July 31, 1984 Australian Rupert Pickrell wrote, “we are enjoying the summer games” of the 1984 Los Angeles Olympics. We are looking forward to entertaining Glenn and Martha Vargas in the near future, when they visit Down Under. The Australians were all in high spirits because of their winning the 1983 […]
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 […]
To Compute or Not to Compute
by Fred Van Sant That is the Question. Whether ’tis better to suffer the wrong angles and other errors of outdated or outrageous designs, or to take up a computer against them–to correct and improve–to achieve a more perfect design–‘Tis a goal much to be desired. But the costs in money and time must give […]
Suggested Procedure For Executing ISO Brightness Contour Maps
by Jack E. Gross Notice to readers. The download features discussed in this article are no longer available from this website. The WORKSHEET, DATA, and GEMCAD FILES may be obtained by E-MAIL from the USFG NEWSLETTER’S EDITOR, Jack Gross, at kookoo@digisys.net. The ISO BRIGHTNESS CONTOUR MAP procedure in this webpage is intended to supplement the […]
Idiots Guide to Gemstone Geometry
by Fred Van Sant Charles Moon told me that on his visit to Australia he found that some of the top cutters there did not understand what all those symbols on the design sheet, like L/W, P/W etc. stood for, and when he tried to explain that they were ratios, they did not know what […]
Getting Rid of Those Bow Tie Blues – Part I
Getting Rid of Those Bow Tie Blues – Part I by Bob Keller Many faceters are familiar with bow ties. High fashion neckwear excepted, bow ties are generally not a good thing in the faceter’s world. Of course I’m referring to the “bow tie effect” in faceted gemstones, which pertains to undesirable dark regions in […]
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 […]
Choosing the Best Angles for Your SRB
by Bob Keller Standard Round Brilliant Standard Round Brilliant Angles for R.I. = 1.54 57 facets + 16 facets on girdle = 73 8-fold, mirror-image symmetry 96 index L/W = 1.000 T/W = 0.546 T/L = 0.546 P/W = 0.435 C/W = 0.121 H/W = (P+C)/W+0.02 = 0.575 P/H = 0.755 C/H = 0.210 Vol./W^3 […]