Gem Notes


If you enjoy rare and precious gemstones and their related stories, here you will find a litany of gemstone ramblings, gemological observations, and useful and time-wasting trivia bought from behind-the-scenes in the rough and cut gem markets of Asia and Africa.


Cobalt 27 – Glass Filled Sapphire PhotoMicrographs

Passing thru the office the other day was a small parcel of cobalt-glass filled sapphire. Technically not really a sapphire, they a manufactured mish-mash composite of dyed-blue-lead-glass and low quality colorless corundum. We thought we could snap a few photomicrographs under the microscope and provide a few slides with annotation of what is going inside and outside of these "Franken-Sapphires".

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Congo Green Tourmaline

Green Tourmaline From Rubaya, Democratic Republic of the Congo Known somewhat casually and unofficially as Congo #2 by Chanthaburi’s hundreds of African rough gemstone dealers, these electric grass-green tourmaline crystals burst out of a new deposit in the Eastern Congo’s Rubaya area in July / August 2019. The crystal sizes and clarity from this mine have been absolutely exceptional with…

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Color Phenomena in Tunduru Sapphire

Holy Cow Batman! Is That A Weird Near Ultra-Violet Sapphire ? No. Its a deeply colored vanadium and chrome rich sapphire from Tunduru in Tanzania. Granted this sapphire does have a powerful fibre-optic parked up its rear-end which explains the intensity of the colors. But, what the fiber-optic does not explain, is, the combination of colors, the directions and also…

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Usambara Effect, Or Not ? Phenomena in Chrome Tourmaline

A strange parcel of crystals from deep in the Oromia state, Southern Ethiopia, came to the office last week. The crystals richly green, had a blue-green color and olive’s color another way. We noticed that several crystals looked reddish with a light when viewed in particular directions. The phenomena appears to be an unusual and not-entirely-explicable interplay between pleochroism, flourescence…

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