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Eight natural-color pistachio pearls
Identification of “Pistachio” Coloured Pearls Treated by Ballerina Pearl Co.

A report on the colour treatment process for these intensely greenish yellow to yellowish-green cultured pearls and the techniques for identifying them.

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Faceted blue zircons
Reversible Colour Modification of Blue Zircon by Long-Wave Ultraviolet Radiation

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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Jaipur, India: The Global Gem and Jewellery Power of the Pink City

Examines Jaipur’s role as a coloured stone cutting and jewellery manufacturing centre, with profiles of 17 companies and their factory, trading and retail operations.

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Micro-Features of Ruby
Inclusions in Natural, Synthetic and Treated Ruby

Provides a visual guide to the internal features of natural, synthetic and treated rubies.

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Beryllium Diffusion of Ruby and Sapphire

The heat treatment of corundum involving lattice diffusion of beryllium (Be) at temperatures over 1800°C has become a major issue in the gem trade.

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Green Amber
Characterisation of “Green Amber” With Infrared and Nuclear Magnetic Resonance Spectroscopy

A peridot-like bright greenish yellow to green gem material called “green amber” has recently appeared in the gem market.

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Gem-Quality Andalusite from Brazil

Widely known as a rock-forming mineral, andalusite is not frequently encountered as a gem material.

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Spectral Differentiation Between Copper and Iron Colourants in Gem Tourmalines
Spectral Differentiation Between Copper and Iron Colourants in Gem Tourmalines

The authors used Vis-NIR spectral measurements combined with LA-ICP-MS data to investigate the usefulness of absorption spectra.

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The Chinese red feldspar controversy: chronology of research up until July 2009

Red copper-containing plagioclase feldspar from Oregon has been available for over a century. In the early 2000s, new localities for copper-bearing feldspar were reported from the Democratic Republic of the Congo and from Tibet or an unspecified locality in China.

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The Radioactive Decay Pattern of Blue Topaz Treated by Neutron Irradiation

A systematic study of 15 neutron-irradiated blue topaz samples was conducted using high-purity germanium (HPGe) digital gamma-ray spectroscopy.

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