Diaspore is an aluminium oxide hydroxide, which is noted within the gem trade for its color-change variety.

First discovered in Russia’s the Ural Mountains 1801, the mineral is named after the Greek for “to scatter” as it was known to break apart when exposed to high temperatures. However, for more than two centuries it was of little gemological interest, due to its pale hues and cutting complications arising from a perfect cleavage. However, the 2006 discovery of Turkish color-change material suddenly brought diaspore into the spotlight.

Known by a variety of unofficial marketing names, including zultanite, csarite and ottomanite – as well as the misnomer “Turkish alexandrite” – these stones display a light yellowish green in daylight and a pale pinkish orange when illuminated by indoor incandescent light sources.