# 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.

## 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 ...

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