Spinel

Mistaken for ruby for centuries - now collected on its own merits.

Mohs hardness: 8
Crystal system: Cubic
Composition: MgAl₂O₄
Colours: Red, Pink, Hot pink (Mahenge)
Origins: Myanmar (Mogok), Tanzania (Mahenge), Tajikistan (Kuh-i-Lal)
Birthstone: August

Spinel forms in the same marble deposits as ruby and was historically misidentified as such - the 'Black Prince's Ruby' and 'Timur Ruby' in the British Crown Jewels are both red spinels.

Unlike most coloured gemstones, spinel is virtually never treated. A natural, unheated spinel is the gemmological default, which adds to its modern collectability.

History

A brief history

Spinel was distinguished from ruby only in 1783 by chemical analysis. The 1980s rediscovery of Mahenge in Tanzania revived the market, with electric pink-red 'neon' material commanding premiums.

Long associated with royal regalia - many 'rubies' in historical European crown jewels are in fact spinel.

Treatments

What to know

Generally untreated - a major selling point

Care & handling

How to wear it

Excellent durability - ultrasonic and steam usually safe
Avoid prolonged exposure to harsh chemicals

Jewellery use

Setting the gemstone

Outstanding daily-wear gemstone. Increasingly chosen as a bespoke alternative to ruby and pink sapphire for engagement rings.

Famous examples

· Black Prince's Ruby (170 ct, spinel)
· Timur Ruby (361 ct, spinel)
· Hope Spinel (50.13 ct)