Demantoid garnet is one of the most brilliant gemstones that exist, yet until recently it was little known except among collectors and gemstone lovers. The name comes from Dutch, meaning “diamond-like”, in reference to its incomparable brilliance and fire. Demantoid by definition is always green, but the exact shade ranges from a very strong yellowish green to nearly the color of a fine emerald. Many stones have a brownish cast. Stones with more intense green coloration are more highly valued, but lighter stones display substantially more fire. The choice of stone color or fire can therefore be a matter of personal preference, with some preferring the less valuable but more lively yellowish-green stones. Russian demantoid nearly always contains asbestos-type inclusions of chrysotile. These golden threads inclusions tend to curve and resemble the tail of a horse, and are therefore referred to as “horsetail” inclusions. Unlike most inclusions which reduce the value of a gemstone, horsetail inclusions can substantially increase the value of a stone. Demantoids from Namibia and Madagascar do not contain horsetail inclusions (although there are contradictory reports on this issue). Demantoid Garnet is the most expensive of all garnets.
