Taaffeite is very rare, and is unique in being the only gemstone not recognized as a new mineral species until it had been faceted. The first specimen was found by Count Taaffe in Ireland, in a jeweller’s box of stones.
It looked like spinel, had a pale mauve tinge, and was cushion-cut, but was eventually found to be a new, doubly refractive (rather than singly refractive like spinel) mineral. Since then, more specimens have been found; these range in hue from red to blue to almost colourless.
Taaffeite occurs in Sri Lanka, China, and the former USSR. No imitation taaffeites appear to exist.