Amateur gem cutter - EFMLS Lapidary Award 1975.Mechanical design engineer/mathematician. Completed all GIA & GAGB gemological courses 1974-80. Author: "Faceting Limits", Gems & Gemology, 1975, and "Diamond Design Revisited", now at Octonus website. Presenter at Diamond Cut Conference, Moscow, 2004.

I am trying to choose between two beautiful round brilliant stones. Both are the same price, XXX diamonds, GIA Cert- Choice 1: 2.04 ct E SI1 No flourescence Measurements: 8.30 x 8.34 x,4.95 Choice 2: 2.01 Ct D SI1 Slight flourescence 8.21 x 8.25 x 89 Do I sacrafice color in favor of a...

User friendly as is, this article is no user guide. Is GIA preparing one? Is it too early? A certain bit of the article sounds like a particularly good start. A certain table (on page 10) makes a rare invitation to ponder if and how those grades show anywhere but on the price tag. Thank you ! Finally a way to read through those intricacies at a ...

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Marcel Tolkowsky was a Belgian engineering student from a family of diamond cutters. In 1919, while studying for his PHD, Tolkowsky wrote a thesis on the proportions for round brilliant cut diamonds that was first published in his book Diamond Design.His formula focused on the proportions that would unleash the most fire and brilliance based on the physics of light, although the concept of ...

In the chart shown here, an interpretation is made of some ranges of proportions given by the GIA based on my assumption that the GIA would concur with previous work done by MSU, Bruce Harding and Jasper Paulsen’s re-interpreted Tolkowsky calculations. But it should be noted that three of the 15 example stones fall outside these oval predictions.

I'll play around with ISO and user head in DC and see what the closest is to GIA pics. Regards, Author/Research Gemologist/CEO Distinctive Gem Inc. ... Bruce Harding ask me :" Please tell people to see my thread 'Girdle Scallops' at 'DiamondTalk' threadid=23362, post #214427 etc., 11-14-02 etc. " ...