The Brilliance of SpheneIn the gemstone world we have a number of technical terms we use to describe the luster of a gemstone. These terms include metallic, adamantine, pearly, silky, vitreous, resinous and waxy. The term adamantine means 'like diamond' and is used to refer to gemstones that have especially high brilliance and intensive dispersion or fire. 
There are very few gemstones that have a luster that deserves to be called adamantine. Diamond is one, of course; the rare demantoid garnet is another (the name 'demantoid' means 'diamond-like'). But one of the members of this exclusive group is a gem that few people have heard of, and even fewer have seen; sphene.
Sphene occurs as translucent to transparent, reddish brown, gray, yellow, green, or red monoclinic crystals. Sphene has an unusually high refractive index (1.843 to 2.110), higher than zircon, ruby and sapphire (but lower than diamond which is 2.417-2.419). But it is sphene's dispersion, or fire, which is truly exceptional, exceeding even that of diamond.
In addition to its exceptional fire, sphene is also strongly pleochroic, meaning it displays more than one color when viewed from different angles. Sphene typically displays at least three colors (colorless, greenish-yellow, reddish) depending on the viewing angle. Sphene is usually found with some inclusions and the rare clean pieces are highly sought after.
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- Prima Pubblicazione: January-04-2008
- Ultima modifica: January-24-2019
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