Spinel

History
Known since the sixteenth century, and sometimes called "balas ruby", spinel has rivaled ruby for hundreds of years. The Black Prince's ruby, which is in the British Imperial State Crown, is actually a magnificent red spinel.

Features
Spinel crystals are frequently octahedral in shape, and are often free from inclusions. Having a variety of colors, spinels can range from deep red to pale pink, to green and dark blue. Despite their hardness (harder than emerald but softer than sapphire) they are brittle and should be gently cared for.

Treatments
Natural spinels are generally untreated, however synthetic spinels are often lab created and used to imitate other stones.

Principal Deposits
Spinel can be found in Myanmar, Sri Lanka, Afghanistan and Brazil.

Rarity 
Small crystals of fine quality spinel are not uncommon, but large stones are increasingly difficult to find, especially the more exotic colors, such as deep blue and purple.