BLUE SPINELS

Blue spinel is a variety of spinel whose colour ranges from soft blue to intense cobalt blue. It is among the rarest precious stones in the world. Its hardness of 8 on the Mohs scale ensures excellent resistance to everyday wear. Blue spinel is naturally untreated in the vast majority of cases, making it one of the very few blue stones that require no artificial heating.

Both stones display a blue colour, but their chemical composition differs. Sapphire is a corundum (aluminium oxide) coloured by iron and titanium. Spinel is a magnesium-aluminium oxide coloured by cobalt or iron. Sapphire has a hardness of 9, compared to 8 for spinel. Blue sapphire is frequently heated, whereas blue spinel remains natural. In terms of brilliance, sapphire offers more intense saturation, while spinel has a softer luminosity. Blue spinel is five to ten times rarer than blue sapphire.

The price of a blue spinel varies considerably depending on hue and weight. Expect to pay €500 to €2,000 per carat for a good-quality blue spinel (1 carat). A cobalt spinel commands €3,000 to €10,000 per carat depending on intensity. Exceptional stones with pure cobalt colour can reach €15,000 to €25,000 per carat. This rarity makes blue spinel a distinguished alternative to unheated blue sapphire.

Blue spinels originate principally from three historic sources. Sri Lanka yields delicate, luminous blues, often with a slight grey tone. Tanzania has produced intense cobalt blue spinels since the 2000s. Vietnam (Luc Yen) has been a major source of cobalt spinels since 1987. Tajikistan and Burma also produce blue spinels, though in very limited quantities.

A cobalt spinel is a blue spinel whose colour is derived from traces of cobalt. This element gives the stone a vivid, luminous and highly saturated blue. It is the rarest and most valuable variety of blue spinel. The finest cobalt spinels come from Vietnam and Tanzania. Their price regularly exceeds €10,000 per carat for gem-quality stones.

No, blue spinel is naturally untreated in the vast majority of cases. More than 95% of blue spinels on the market receive no heating or chemical enhancement. This is one of its greatest strengths compared to blue sapphire, and it is particularly appealing to lovers of natural stones. Bonnot Paris guarantees the absence of treatment for every blue spinel in its collection.

Yes, blue spinel possesses all the qualities required for an engagement ring. Its hardness of 8 on the Mohs scale ensures excellent longevity. It withstands daily wear without requiring a protective setting. Its rarity, exceeding that of blue sapphire, makes it a particularly meaningful choice. It is a refined and confidential alternative for those seeking something truly original.

Blue spinel pairs beautifully with all precious metals. White gold and platinum preserve a pure reading of the blue tone and suit intense cobalt spinels particularly well. Yellow gold creates a warm contrast with softer blues. Rose gold offers a romantic dialogue with greyed tones. The choice ultimately depends on the chromatic character desired and the precise colour of the stone.