Little-known yellow or yellow-green gemstone, first discovered in Namibia in 1962. Also found in mountainous area of Mexico and Switzerland. The first miners to find it thought it was a type of beryl and tried to cut only the green, which would be a valuable light-colored emerald if they had been right. It's fairly soft for jewelry, though, at 5.5 on the Mohs hardness scale (beryls are much harder) and extremely rare -- it's usually snapped up by serious gem collectors rather than being made into jewelry (though discovery of bigger supplies could change that).