Spinel

Spinel is a rare and highly prized gemstone. In recent decades it has enjoyed a renaissance and today ranks among the most sought-after coloured gemstones.

Spinels from the marble region of Mogok have always been regarded as important companions of ruby-bearing marbles. Where high-quality spinel occurs, rubies are frequently found as well.

Spinel has a Mohs hardness of 8 and no pronounced cleavage. This makes it very durable and excellently suited to jewellery. Its broad colour range extends from red through pink, blue-violet and grey to black.

Its cubic crystals often form perfect octahedra. In antiquity, such naturally grown crystals could be used as gemstones with relatively little cutting.

Historically significant

The Black Prince’s Ruby has been in the possession of the English Crown since 1367. Despite its name, it is not a ruby but a red spinel. The stone probably comes from the famous Kuh-i-Lal mine in present-day Tajikistan.

Many of the most famous “rubies” of European crown jewels, among them the Black Prince’s Ruby and the Timur Ruby, later proved to be red spinels.

Ruby and spinel could only be reliably distinguished from one another with the methods of modern gemmology. One important characteristic is their different refraction of light; in addition, spinel shows no birefringence, whereas ruby does.

Particularly sought after today are intensely glowing red and pinkish red spinels from Mahenge in Tanzania, whose strong colour is caused by chromium. Equally legendary are the rare cobalt blue spinels from Luc Yen in Vietnam. Spinels from Mogok in Myanmar also regularly achieve top prices.