Titanite (Sphene)

Titanite is a calcium titanium silicate, known in the gem trade as sphene. It has a dispersion of about 0.051, higher than diamond's 0.044, so a well-cut stone shows strong flashes of spectral color. It also has very strong double refraction, which makes the back facets look doubled. Titanite is fairly soft, so it is mostly a collector's stone and a choice for earrings and pendants.

Titanite and sphene

The mineral's official name is titanite, after the titanium in its chemistry. Sphene, from the Greek word for wedge, describes its typical wedge-shaped crystals. Mineralogists formally adopted titanite as the species name in the early 1980s. The gem trade still uses sphene widely, and the two names mean the same material.

Dispersion and fire

Dispersion is the splitting of white light into spectral colors as it passes through a gem. A stone with high dispersion shows colored flashes, called fire. Diamond's dispersion is 0.044. Titanite's is around 0.051, and demantoid garnet is close at about 0.057. The diamond optical properties page explains dispersion and how cut controls it.

The table compares titanite with other gems known for fire.

Titanite sits between the man-made simulants and diamond. The pages on moissanite and cubic zirconia cover the two high-dispersion simulants.

Titanite's yellow, green or brown body color partly masks its fire. Lighter stones show it better. Its luster is adamantine to resinous, close to diamond, and its refractive index of about 1.84 to 2.11 is above the range of a standard gem refractometer.

Strong doubling

Titanite is doubly refractive, with a birefringence of about 0.100 to 0.135. That is among the highest of any gem, higher than zircon. Light entering the stone splits into two rays that travel at different speeds. The back facets and edges appear doubled when viewed through the table, and even a casual look with a loupe shows it.

Doubling helps a gemologist identify titanite. It also gives faceted titanite a slightly soft, fuzzy look when cut poorly. Cutters orient the table close to an optic axis to reduce doubling face-up or to balance it with fire. The birefringence and double refraction page explains how this works.

Pleochroism

Titanite is strongly trichroic. Depending on the viewing angle, a green stone may show yellow, green and reddish brown. This adds to the play of colors in a faceted gem and is one more clue for identification. The pleochroism page describes trichroism and how gemologists see it with a dichroscope.

Colors

Titanite comes in yellow, green, brown, orange, black and, rarely, red or pink. Green stones colored by chromium are sometimes called chrome sphene. Yellow-green and green material is the most popular in jewelry. Heating can turn some yellow or brown titanite orange, red or reddish brown.

Sources

Titanite forms in igneous rocks such as granite and syenite, and in metamorphic rocks including schist, gneiss and marble. Gem crystals often come from alpine-type fissures, open cracks where minerals grow freely. The igneous rocks and gemstones page covers how such rocks form.

Gem titanite comes from:

• Madagascar, a major source of yellow to green gem material.
• Pakistan, which produces fine crystals and gem rough from its northern mountains.
• Brazil, especially Minas Gerais.
• Sri Lanka, Myanmar, Russia, Mexico (Baja California), Austria, Switzerland and the United States.

Clean, facetable crystals over a few carats are uncommon, so larger stones are rare.

Cutting titanite

Titanite is challenging to cut. It is soft and brittle, with distinct cleavage and parting, so it can chip during cutting. Cutters must also balance doubling and fire. Round brilliants, ovals and cushions show fire well. Transparent material is faceted, while included material becomes cabochons.

Durability and care

With a hardness of 5 to 5.5, titanite scratches easily, even from quartz dust. It also chips at facet edges. It suits earrings, pendants and brooches better than rings. A titanite ring needs a protective bezel or halo setting and careful wear. The gemstone durability page compares wearability.

Clean titanite with warm soapy water and a soft brush. Avoid ultrasonic and steam cleaners, sudden temperature changes and contact with harder gems in storage.

Telling titanite from look-alikes

Titanite's yellow-green color can resemble peridot, chrysoberyl, demantoid, zircon and green sapphire. Its extreme doubling, strong trichroism and high dispersion separate it. Its refractive index is above the refractometer limit. Zircon also shows doubling and fire but is harder and usually lacks strong trichroism. Demantoid is singly refractive, so it shows no doubling.

Frequently asked questions

Does titanite have more fire than diamond?

Yes. Titanite's dispersion of about 0.051 is higher than diamond's 0.044. Its body color can hide some of that fire.

Is sphene the same as titanite?

Yes. Titanite is the official mineral name, and sphene is the traditional name still used in the gem trade.

Can titanite be worn in a ring?

It can, but it scratches and chips easily. A protective setting and gentle wear help.

Why do titanite facets look doubled?

Titanite has very strong double refraction, so each ray of light splits in two inside the stone and back facets appear doubled.