Background and Primer for the Online Tangent Ratio Converter by Bob Keller, Old Pueblo Lapidary Club A mathematical procedure known as tangent ratio conversion or translation is frequently employed by faceters to optically optimize or tweek a gemstone …

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 Whether ’tis better to suffer the wrong angles and other errors of outdated or outrageous designs, or to take up a computer against them–to correct and improve–to achieve a more perfect design–‘Tis a goal much …

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@di …

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 ra …

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 facet …

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 …

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/ …