Umba sapphire
Encyclopedia
Umba sapphire is a unique type of fancy sapphire
Sapphire
Sapphire is a gemstone variety of the mineral corundum, an aluminium oxide , when it is a color other than red or dark pink; in which case the gem would instead be called a ruby, considered to be a different gemstone. Trace amounts of other elements such as iron, titanium, or chromium can give...

 discovered circa 1960 in the Gerevi Hills, north of the Umba River
Umba River (Tanzania)
The Umba River is located in northeastern Tanzania in Tanga Region. It rises in Schageiuforest in the West Usambara Mountains at 2,000 m altitude and flows on the north side of the mountain range to the east. At Lelwa empties the Mbalamu River who comes from the extreme north of the Usambara...

 in the Umba Valley
Umba Valley
Umba Valley is a geographic area in Tanzania and the world's only source of Umba sapphires.The Umba River flows through the Umba Valley.Specifically, Umba Valley is located in the north of Usambara Mountains in the Tanga Region of Tanzania.-References:...

 of Tanzania
Tanzania
The United Republic of Tanzania is a country in East Africa bordered by Kenya and Uganda to the north, Rwanda, Burundi, and the Democratic Republic of the Congo to the west, and Zambia, Malawi, and Mozambique to the south. The country's eastern borders lie on the Indian Ocean.Tanzania is a state...

. Umba sapphires exhibit coloration not common to sapphires sourced from other parts of the world, and are recovered from the alluvial deposits of the Umba River (Tanzania)
Umba River (Tanzania)
The Umba River is located in northeastern Tanzania in Tanga Region. It rises in Schageiuforest in the West Usambara Mountains at 2,000 m altitude and flows on the north side of the mountain range to the east. At Lelwa empties the Mbalamu River who comes from the extreme north of the Usambara...

.

, the Tanzanian government prohibits export
Export
The term export is derived from the conceptual meaning as to ship the goods and services out of the port of a country. The seller of such goods and services is referred to as an "exporter" who is based in the country of export whereas the overseas based buyer is referred to as an "importer"...

of these sapphires.
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