Demantoid garnet, diamond and pearl brooch, circa 1890.

This brooch is in good condition, commensurate with its age.

The demantoid is one of the most dispersive gemstones that exist, yet until recently it was little known except among collectors and stone lovers. It is a green garnet, or rather the star of the green garnets. Not without reason does it bear a name which means 'diamond-like'. The name comes from the Dutch and makes reference to the outstanding quality of this gem, its incomparable brilliance and fire.

The demantoid belongs to the garnet family, and is actually a variety of the garnet mineral andradite. But it is more than that: it is the most expensive kind of garnet and one of the most precious of all gemstones. It is highly prized because of its rarity, coupled with an intense luminosity. Demantoid has an extremely high refractive index 1.880 to 1.889. Its high dispersion is also remarkable, its ability to split the light which comes in through the facets and break it down into all the spectral colours. The demantoid surpasses even diamond in its dispersive properties.

This stone comes in many shades of green, from a slightly yellowish green to a brownish green with a golden glow. Particularly precious is a deep emerald green, though this only occurs very rarely indeed. It is not only fine and unusual, but the specimens are also mostly small, large ones being extremely rare. Once cut, only a few stones weigh more than two carats, and most of them hardly exceed one. And even if you come across one set in a piece of jewellery, it is always likely to be a small stone.

After its discovery in 1868 in Russia's Ural mountains, the demantoid rapidly proceeded to become a much desired gemstone. It found fame among the finest jeweller's workshops in Paris, New York and St. Petersburg. First and foremost, Russia's star jeweller Carl Fabergé adored it for its tremendous brilliance and loved to incorporate it in his precious objects.

The demantoid garnet has long been prized for its rarity and brilliance, it remains today one of the most unusual stones available in jewellery in the world.