SPINELS

Spinel is a crystalline precious stone that occurs naturally in a wide range of colours. Its hardness of 8 on the Mohs scale gives it excellent durability. It differs from ruby and sapphire in its mineral composition. Its transparency and brilliance place it visually alongside the most prestigious coloured stones.

Spinel and ruby can display strikingly similar red hues, yet they are distinct stones with different mineral compositions. Ruby owes its colour to chromium, as does spinel — but the two belong to entirely different mineral families. They were confused with one another for centuries: the famous "Black Prince's Ruby" in the British Crown Jewels was not identified as a spinel until 1851. In terms of hardness, ruby scores 9 against spinel's 8 on the Mohs scale, though spinel remains perfectly suited to daily wear.

The price of a spinel varies considerably depending on colour, weight and origin. For a good-quality stone of around one carat, expect to pay €300 to €1,500 per carat. Mahenge pink spinels from Tanzania reach €3,000 to €10,000 per carat. "Jedi" red spinels from Burma can exceed €15,000 per carat. Cobalt blue spinels remain the rarest and most expensive of all. At equivalent quality, a spinel typically costs three to five times less than a ruby.

Spinels come principally from four historic sources. Burma (Mogok) yields the legendary neon-red "Jedi" spinels, the most coveted of all. Tanzania (Mahenge) has been the world benchmark for fluorescent pink spinels since 2007. Tajikistan (Kuh-i-Lal) produces pink spinels with soft, historically significant hues. Vietnam (Luc Yen) offers spinels across many colours, including rare blues. Sri Lanka rounds out supply with more modest but notable production.

Spinel is one of the very few precious stones that is naturally untreated. More than 95% of spinels on the market receive no heat treatment or chemical enhancement whatsoever — one of its most compelling advantages over ruby or sapphire. This quality appeals particularly to enthusiasts and collectors alike. Bonnot Paris guarantees the absence of treatment for every spinel in the collection, confirmed without exception by an independent certificate.

Yes, spinel is an excellent choice for an engagement ring. Its hardness of 8 on the Mohs scale ensures lasting durability and stands up to everyday wear without requiring a protective setting. Its natural rarity and untreated character make it a particularly meaningful choice. Spinel offers a distinctive alternative to classic sapphire and ruby, and its broad colour palette makes it possible to find a truly one-of-a-kind stone.

Mahenge spinel refers to the fluorescent pink spinels discovered at the eponymous deposit in Tanzania. The landmark find dates to August 2007, when an exceptional 52 kg crystal was unearthed — a discovery that transformed the spinel market. Mahenge colour is defined by a unique neon-pink fluorescence, the result of a rare combination of chromium and the virtual absence of iron. Mahenge spinels fetch €3,000 to €15,000 per carat depending on quality.