Wednesday, January 17, 2007

Some of the the world’s rarest gemstone varieties

Painite has in years past been described by the Guinness Book of World Records as the rarest gem mineral. As of early 2005 there were eighteen known specimens, all numbered and accounted for. Painiteis pink to red to brown in color, very strongly pleochroic (showing different hues from different angles) and it fluoresces a lovely green under short wave UV. It comes from Mogok and Kachin State in Myanmar and was named after its discoverer, British gemologist Arthur Charles Davy Pain.

Serendibite is a cyan colored stone that comes from Sri Lanka. It boasts an unusually complex formula consisting of calcium, magnesium, aluminum, silicon, boron and oxygen. So far there exist three faceted specimens of 0.35 carats, 0.55 carats and 0.56 carats. The first two were discovered by rare stone specialist D. P. Gunasekera and purchased by the late Prof. E. J. Gubelin of Switzerland. The name comes from the old Arabic term for Sri Lanka, Serendib, as referenced in The Sixth Voyage of Sinbad and elsewhere.

Dumortierite is a fibrous variably colored aluminium boro-silicate mineral that is primarily used as an ornamental stone. It has a deep violet to blue color that is quite attractive and unusual. Although rarely used as a gemstone due to its lack of clarity, its hardness and bright color make it useful for the manufacture of all kinds of carvings. Massive dumortierite can be carved into cabochons, beads, sculptures, eggs and spheres. Facet quality dumortierite is extremely rare and few specimens exist anywhere.

Petalite is a colorless and glassy looking but some stones are pale yellow and a pink chatoyant specimen has also been reported from South Africa. Little crystalline material is ever available for cutting and faceted stones are uncommon. Large clean stones are always in demand by collectors. The name petalite is derived from the Greek word 'petalos' meaning leaf, an allusion to the cleavage.

Grandidierite is a bluish green mineral found primarily in Madagascar. The first and so far only clean faceted specimen, from Sri Lanka, was originally mistaken for a serendibite and subsequently purchased in May 2000 by Prof. Gubelin from Murray Burford. The mineral is named after French explorer and natural historian Alfred Grandidier, who among other things unearthed bones from the extinct half-ton elephant bird in Ambolisatra, Madagascar.

Jeremejevite, is a colorless, sky blue or pale yellow stone, the highest quality of which comes from Namibia. In nature it occurs in small obelisk-shaped crystals and has in the past been mistaken for aquamarine. It was named after Russian mineralogist Pavel Jeremejev who discovered the mineral in 1883.

Majorite is a purple form of garnet that was discovered in 1970 in the Coorara meteorite near Eucla, Western Australia. The species is named after Alan Major who researched high-pressure garnet formation.

Taaffeite, is a mauve to purple to red stone named after Bohemian-Irish gemologist Edward Taaffe who discovered the first one from a box of Sri Lankan spinels in 1945. The stone displayed a double refraction which was uncharacteristic of spinel. If you could round up all the faceted taaffeitescurrently in existence they would fill about half a cup.

Musgravite chemically and optically similar to taaffeite but a lot more rarer. Facetable musgravite was first reported in 1993 and as of 2005 there were eight such specimens, three of those identified by Murray Burford. The mineral was discovered in 1967 at the Musgrave Range in South Australia, but has since then turned up in Greenland, Madagascar and even Antarctica.

Benitoite is found only in San Benito County, California. The stone is a strong blue with a dispersion similar to that of diamond, and fluoresces an intense blue-white under UV light.

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