By Elena Petrova
1 French mineralogist Alfred Lacroix found the first reported samples of grandidierite in 1902. He discovered the gemstone at the cliffs of Andrahomana in southern Madagascar.
2 Grandidierite was named after French explorer and naturalist Alfred Grandidier (1836-1912).
3 Grandidierite is extremely rare. This gem is at least number three in the list of the rarest 10 gemstones on the planet.
4 In addition to Madagascar, very little Grandidierite has been found in New Zealand, Norway, Suriname, Algeria, Italy, Malawi, India, the United States, Canada, Antarctica and the Czech Republic.
In 2014 transparent with several fine quality faceted material was found outside of Tarnomaro, Madagascar, near the site where the first pieces of grandidierite were found. It occurs in the form of strong bluish green to greenish blue translucent to transparent crystals measuring up to 15 × 7 × 3 cm.
5 Most of Grandidiorite is opaque. Even gem-quality material is often translucent (semi-transparent), and is cut into cabochons about 1 carat to 10 carats and up. Ratio of gem-quality crystals to rough is about 1 in 10,000 (MultiColour Gems). Tranomaro deposit has produced only about 60 grams (300 carats) of eye-clean crystals.
6 Gemstone quality Grandidierite has in shades of blue and green with the soft neon blue. The color itself is caused by minute traces of iron impurities and the blue component increases with Fe content. It is transparent to translucent with a pale yellow to colorless, greenish blue, and blue trichroism.
7 Grandidierite appears to be two or even three different colors depending on which angle it is viewed. Grandidierite is pleochroic - it can flash from yellow to green to blue and even colorless in some examples.
8 According to GIA’s Gems & Gemology, gem-quality grandidierite of “facetable size” was “almost unheard of” in the market before the summer of 2015.
9 Guinness World Records lists the largest known Grandidierite in the world as the 78 carat specimen owned by Joseph Fam from Singapore in South East Asia. Wilensky Gallery in New York City has three amazing grandidierite from the Tranomaro region of Madagascar. They weigh 2.86, 3.14 and 4.96 carats and are priced at $69,000, $78,000 and $129,500.
10 Scientists have synthesized grandidierites for special projects. However, there is no known use for this synthetic material in jewelry.