Sunday, August 18, 2013

Rare Gemstones IV

Sri Lanka Padparadscha sapphires are a delicate color that is a combination of pink/coral and orange/red.

Padparadscha sapphires are one of the most expensive sapphires, with prices similar to those fetched by fine rubies or emeralds. Prices for padparadscha sapphires are difficult to determine because some value them at the highest range of a pink sapphire at $4,800/carat, while others place them in their own category of up to $30,000/carat. Much depends on the size and quality of the stones.
Benitoite is a rare blue barium titanium silicate mineral, found in hydrothermally altered serpentinite.

It was first described in 1907 by George D. Louderback, who named it benitoite for its occurrence near the headwaters of the San Benito River in San Benito County, California. It is the sole source of gemstone quality material. Benitoite is California's official state gem.
Demantoid garnet was discovered in 1868 in Russia's western central Ural Mountains. Possessing an unusual green color and a dispersion greater than that of diamond, it quickly became a treasured and expensive gemstone. From the time of the demantoids find until about 1919, they were popular in Russia as Fabergé made jewelry with them.

A significant new find of demantoid and andradite took place in Namibia in 1996 at what is now dubbed the "Green Dragon" mine. Around 2009, there was a significant discovery of demantoid and andradite garnet in Madagascar.
Black opal is the rarest and most valuable of all opals. 97% of all opals come from Australia. Opal is Australia's national gemstone.

Opal is unique among gemstones. No two are ever exactly alike and the colours and patterns within each stone can change with the angle of view.
Taaffeite is named after its discoverer Richard Taaffe who found the first cut and polished gem in November 1945.

In 1951, chemical and X-ray analysis confirmed the principal constituents of taaffeite as beryllium, magnesium and aluminium. Taaffeite occurs in carbonate rocks alongside fluorite, mica, spinel and tourmaline. This extremely rare mineral is found in alluvial deposits in Sri Lanka and southern Tanzania.