Characterises a suite of 40 natural brown to black diamonds from this deposit so that they can be distinguished from suspected treated black diamonds.
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A simple chart of optical defects in diamond, including those that produce colouration and fluorescence colours.
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How variations in UV lamp output can affect observed fluorescence colour and intensity.
Read MoreThe GIA diamond cut grading system described here includes the components of brightness, fire, scintillation, polish and symmetry, as well as weight and durability concerns, into a single overall grade for cut quality for standard round brilliants.
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Knowledge of type allows gemmologists to better evaluate if a diamond might be treated or synthetic, and whether it should be sent to a laboratory for testing.
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This article reviews the GIA Laboratory’s history of reporting on certain types of graining which are often the only characteristics present in large, high-clarity, high-colour diamonds.
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This article illustrates the various features in filled diamonds and explores the best techniques for examining them.
Read MoreSynthetic moissanite is much closer to diamond in overall appearance and heft than any previous diamond imitation; this article reports on how to identify and characterise it.
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HPHT-treated type I diamonds of various colours may exhibit unusually intense fluorescence at the facet edges and junctions.
Read MoreTwo major sources of error make spectroscopically determined colour grades unreliable.
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