Madagascar sphene is the gem variety of the mineral titanite (calcium titanium silicate), known in the trade by its older name sphene from the Greek for wedge, after the typical wedge-shaped crystal habit. Madagascar is one of the principal modern sources of facetable sphene, alongside Pakistan, Brazil and Russia, with material recovered from metamorphic rocks of the central highlands around Antsirabe, Brickaville and the Itasy region.

Material character

The species is famous for two qualities: extreme dispersion (0.051) higher than that of diamond, which produces vivid spectral fire in well-cut stones, and strong birefringence near 0.105 to 0.135, which produces obvious doubling of facet edges visible at ten-power magnification. The colour palette runs from pale yellow through saturated chrome green, golden yellow, brownish orange and rarely a saturated yellow-green that resembles fine Russian Khibiny material.

Refractive indices are 1.85 to 2.05, exceptionally high among coloured gems; specific gravity sits near 3.5, and hardness is a soft 5 to 5.5. The combination of low hardness and pronounced cleavage means sphene is unsuited to ring use without protective settings; it is best as an earring, pendant or collector stone.

Treatment and trade

Heat treatment is occasionally applied to lighten brownish stones, although the bulk of Madagascan production reaches the market untreated. The species sees little to no synthetic competition in commercial channels. Most rough is exported to Sri Lanka, India and Bangkok for cutting; faceting calls for an experienced lapidary because of the cleavage and the need to manage the strong doubling.

For collectors, fine Madagascan sphene offers some of the most spectacular dispersion-driven fire available in any natural gem and remains comparatively accessible against equivalent demantoid garnet or zircon at similar size.