Benitoite is one of the rarest gemstones in the world. While the mineral benitoite itself is quite rare, large gem-grade crystals have only been found in one very small region of California, and in commercial quantities only on one small hill in San Benito County. When first discovered in 1907, it was thought to be sapphire, and indeed the color is nearly identical to the finest sapphires–and like sapphire, the color comes from minute traces of the element titanium. Not long after, it was described as a new gem mineral and commercial mining began but didn’t last long as the deposit was too small. Intermittent minor-scale mining has occurred sporadically since then, with the last significant mining done for a few years in the early 2000’s, and since then the mine has been inactive except for searching of the mine dumps for material missed by the commercial operations.
The intense blue color of benitoite makes it highly attractive as a gemstone. In addition, it has a relatively high refractive index (1.757 to 1.804) and high dispersion (0.039 to 0.046). This makes a faceted benitoite look a bit like a sapphire-blue diamond. However, unlike sapphire or diamond, benitoite is fairly soft at 6-6.5 on the Mohs scale.
There are no named varieties or species of benitoite.
Where is it found
Gem benitoite has been found only at one location, the Dallas Gem Mine (or Benitoite Gem Mine) in San Benito County, California.
Benitoite is not treated.
Use in jewelry
Benitoite is relatively soft and generally fairly small. As a result, its often used as an accent stone in jewelry or simply kept as a collector’s loose gemstone.
You can look at my current inventory of loose gemstones online here: http://www.earthstreasury.com/product-category/gemstones/collector/benitoite/