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Fancy-color diamonds from Lomonosov, Russia.
Geology and Development of the Lomonosov Deposit, North-Western Russia

Reviews diamond discoveries at the Lomonosov deposit, as well as the geology of the Arkhangelsk kimberlite province.

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Dyed Purple Hydrophane Opal

Opals with an unusual purple bodycolour and strong play-of-colour have recently appeared in the market.

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Play-of-colour opal from Wegel Tena, Wollo Province, Ethiopia
Play-of-colour opal from Wegel Tena, Wollo Province, Ethiopia

A new opal deposit was discovered in 2008 near the village of Wegel Tena, in the volcanic rocks of Ethiopia’s Wollo Province.

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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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Demantoid and topazolite from Antetezambato, Northern Madagascar: review and new data

An important deposit of andradite, containing demantoid and topazolite varieties, has been mined near the village of Antetezambato in northern Madagascar since early 2009.

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Peridot from Sardinia, Italy
Characterisation of Peridot from Sardinia, Italy

Gem-quality peridot is occasionally found as mantle xenoliths within basalts near Pozzomaggiore.

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G. Robert Crowningshield: A Legendary Gemmologist

G. Robert (Bob) Crowningshield has made many significant contributions to the study of gems and the science of gemmology.

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Yellow Mn-rich Tourmaline from the Canary Mining Area, Zambia

The most important source of yellow gem elbaite is the Canary mining area in the Lundazi District of eastern Zambia.

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Nanocut Plasmaetched Diamonds
Cutting Diffraction Gratings to Improve Dispersion (“Fire”) in Diamonds

A new microlithography process developed to create high-resolution diffraction grating patterns on portions of certain facets can improve the dispersion of light and thus the amount of “fire” in a diamond.

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A Gemological Pioneer: Dr. Edward J. Gübelin

During a career that spanned more than 65 years, the eminent Swiss gemmologist Dr. Edward J. Gübelin (1913–2005) built a monumental legacy.

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