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

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".

Read More

Congo Green Tourmaline

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…

Read More

Color Phenomena in Tunduru Sapphire

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…

Read More

Usambara Effect, Or Not ? Phenomena in Chrome Tourmaline

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…

Read More

Twinning in Unheated Mozambique Ruby

Twinning in Unheated Mozambique Ruby

Red, orange and pink parallel lines show through in the twinning in this unheated natural Mozambique ruby. While a relatively common feature in rubies from Mozambique, they generally have to be placed under the dark-field type lighting of a gemological microscope to be seen so easily. In the rough-gemstone stage, should the twinning be quite prominent, the preforming manufacturer will…

Read More