Description
This Tanzanian Colour Change Garnet displays a very rare Usambara effect in conjunction with its colour change.
The “Usambara Effect” is rarely seen in gemstones and is named after the Usambara mountains in the Umba valley of Tanzania, a region where this effect was first observed and that has been a rich source of colour change and Usambara effect gemstones.
When viewed in outside sunshine or when using daylight equivalent white light, this gemstone displays an olive brown colour with flashes of red around the outer facet edges, which is known as the “Usambara effect” and is rarely seen in colour change Garnets.
The Usambara effect is occurring because of the increased or “doubled” path lengths of light produced by internal reflections within the gemstone creating the “Usambara Effect”.
The red flashes caused by the Usambara effect are clearly seen around the outer edges of this olive brown coloured Garnet make this a very visually appealing aspect of this gemstone and is sure to dazzle when warn in outside sunshine!
When it is exposed to warm incandescent light this garnet displays a very rich red colour producing the colour change effect in this gemstone.
So while the Usambara effect is not something typically seen in colour change gemstones, they are sought after curiosities of nature and highly appreciated by gem collectors, connoisseurs and gemmologists alike.
This gemstone weighs in at 1.15cts with only minor inclusions seen in the gemstone.
This stone is untreated and completely natural, it has a clarity rating of VS – Very slightly included.
A video of this gemstone stone displaying its impressive colour changes can be seen by clicking the video button below:
