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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How variations in UV lamp output can affect observed fluorescence colour and intensity.
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A simple chart of optical defects in diamond, including those that produce colouration and fluorescence colours.
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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.
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.
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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This article illustrates the various features in filled diamonds and explores the best techniques for examining them.
Read MoreTwo major sources of error make spectroscopically determined colour grades unreliable.
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HPHT-treated type I diamonds of various colours may exhibit unusually intense fluorescence at the facet edges and junctions.
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