Determines whether blue zircon, inadvertently altered to brown by exposure to long-wave UV radiation, can be restored to its original colour through the use of incandescent light.
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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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Describes the occurrence of iridescence, and the role of differential etching, in quartz crystals from India’s Jalgaon District.
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Examines a collection of chrysoberyl samples from these sapphire placer deposits to determine their distinct mineralogical and chemical properties.
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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.
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An introduction to Moroccan amethyst, which features distinctive color zoning and inclusions.
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 MoreWidely known as a rock-forming mineral, andalusite is not frequently encountered as a gem material.
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The Argyle diamond mine is the only known source of type IaB hydrogen- and nitrogen-rich diamonds coloured grey to blue to violet.
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