Tucked away in a remote pocket of San Benito County, California lurks a mineral marvel that puts sapphires on notice - the elusive Benitoite. Discovered in 1907 by James Marshall Couch, this prismatic prima donna puts on quite the light show - fluorescent under blacklight and sparkling with diamond-like fire, though it's a tad more delicate at 6 on the Mohs scale (maybe it's just sensitive).

In over a century since then, its single commercial producer (the Benitoite Gem Mine) has coughed up a measly 5,000 carats of faceted stones. While it occasionally makes cameos in nine other global locations, it saves its gem-quality performances exclusively for California. These crystalline divas typically play it small under 1 carat, though one show-off topped the scales at 15.42 carats.