Benitoite

(via ICA )

A beautiful sapphire blue colored stone, benitoite is a rare mineral and occurs in gem quality crystals only in the Diablo Range of California. Benitoite is named after the country in which it occurs—San Benito County. Having hardness of only 6½ on the Moh’s scale, benitoite is one of the rarest of all mineral that are suitable for jewelry.

Sapphire-blue benitoite is found in association with another rare titanium mineral—neptunite—in a matrix of white natrolite. Stones over 2 carats were very rare until when a deposit with larger stones….some weighing up to 6 carats….was found at the Benitoite Gem Mine in California. A pink benitoite has been reported, but it is extremely rare. Colorless crystals of benitoite are not uncommon but are not considered worth cutting. Benitoite also has been found as tiny grains in rock in a few other Californian localities, as well as in Belgium, Japan, Korea, and Texas. However, these deposits are of little importance to the gem trade.

There are several versions as to who actually discovered the stone; but one of the most likely accounts is that the in late 1906 a prospector by the name of James Crouch was searching for mercury and copper minerals in the area of the San Benito river in California. He discovered some blue crystals in a vein of white natrolite, and it was at first believed that they were sapphires. However, because of the strong colorless to blue dichroism revealed by the stones on subsequent testing by a jeweler, the precise identity of the stone was subsequently questioned. Crystals from this new find were sent to Dr George Louderback, Professor of Geology at the University of California at Berkeley. He identified these as a new mineral, and named it benitoite after its country of origin.

In October 1985, the Governor of California named benitoite California’s official State Gemstone.

Interestingly, it has been claimed that a large benitoite weighing over 6 carats was presented to Benito Mussolini in 1938 by the then Italian Ambassador to the United States. This led some, who were not familiar with the stone’s origin, to assume that benitoite was named after Benito Mussolini…because of the similarity with his first name.

Benitoite is a very beautiful gemstone, although it is not very well known compared to other colored gemstones. It has high refractive indices (1.757 – 1804) and a high dispersion (0.046 vs diamond’s 0.044). Thus the ‘fire’ of benitoite approximates that found in diamond; but the visual effect is masked by the dark blue body color of the stone. Interestingly, blue benitoite fluoresces and identifying strong bluish white when exposed to short wave ultraviolet wavelengths.

Gradually this lovely sapphire blue colored gemstone is beginning to receive the recognition it deserves, and it can now be found more frequently in fine jewelry…particularly in the USA.