Bruce Harding

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.

Last 5 articles of this author

Dimensioning Diamonds

There have been inconsistencies and vagueness about how diamond dimensions are defined. This clarifies the terms and differences and suggests better alternatives. Due to QWERTYism* none of this will change. Star Dimensions The GIA Diamond Course (1974 for me), described the table and stars of a round br...

Dimensioning Diamonds VIEW POST

Why are the ‘Best’ Cuts on the Edge of the Table-Bezel Zone?

The Probable Reason Garry Holloway1 was the first to suggest a meaningful explanation for this: he suggested that, because there is a small difference between pavilion main & half facet slopes (less than 2º in a typical round brilliant), this may cause one to be dark when the other is bright – producing contras...

Why are the ‘Best’ Cuts on the Edge of the Table-Bezel Zone? VIEW POST

A Study of Colored Stone and Diamond Cutting Angles

Introduction From Faceting Limits: The pavilion and bezel slopes commonly recommended for faceting are the result of trial-and-error and human judgment. This explains why references differ in their recommendations. Trial-and-error is an effective way to solve complex problems until a better way comes along, bu...

A Study of Colored Stone and Diamond Cutting Angles VIEW POST

Fractioning of Color by a Gem

This article shows an interesting effect of dispersion whereby color components are progressively diverted from the spectrum, as in 'fractional distillation' or 'fractional crystallization' of liquids. White Light & Rays White light is composed of combined colors; different colors can be combine...

Fractioning of Color by a Gem VIEW POST

Cutting Ovals

Simple but Ugly Oval Figure 1 shows a 4:3 oval (e.g. 8x6mm) cut using the same indexes (azimuths) as a standard round brilliant and also the same slopes for the main facets (the half-facet slopes must be modified for desired depth and proper meets). The pavilion, at the upper end, shows a trace of end-facet ...

Cutting Ovals VIEW POST

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