Anatase Value, Price, and Jewelry Information

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Round brilliant-cut anatase, 0.13 cts, 2.9 mm, Brazil. © The Gem Trader. Used with permission.

Anatase occurs in many beautiful colors, such as deep indigo and amber yellow. However, these rare gems are seldom transparent and are usually found as very small crystals. They’re hardly ever faceted, except as curiosities for gem collections.

Anatase Information

Data Value
Name Anatase
Alternate Common Names Octahedrite, oisanite.
Crystallography Tetragonal; crystals pyramidal, striated; also tabular and prismatic.
Crystallographic Forms
Refractive Index 2.488-2.564
Colors Black, red-brown, brown, blue, deep indigo-blue; colorless to grayish, greenish, blue-green, lavender, pale yellow, yellow brown. Banding due to zonal growth often visible.
Luster Adamantine, sometimes slightly metallic.
Hardness 5.5-6
Fracture Subconchoidal
Specific Gravity 3.82-3.97
Birefringence 0.046-0.067
Cleavage Perfect 2 directions
Dispersion 0.213 (o); 0.259 (e).
Luminescence None
Luminescence Present No
Transparency Translucent to transparent (rare). Pyramidal crystals or gems with dark tones may appear almost opaque.
Absorption Spectrum Not diagnostic
Formula TiO2
Pleochroism Strong in deeply colored crystals: brown/yellow-brown/greenish-blue.
Optics = 2.534-2.564; e = 2.488-2.497. Uniaxial (-). Some crystals may be biaxial. See "Identifying Characteristics" below.
Optic Sign Uniaxial -, Biaxial -
Etymology From the Greek anatasis for “extension,” since the anatase “octahedron” is really a tetragonal bipyramid and, thus, elongated with respect to the octahedron of the isometric system. Octahedrite alludes to this “double pyramid” shape. Oisanite references the type locality, St Christophe-en-Oisans, France.
Occurrence Gneisses, schists, and other metamorphic rocks; as detrital grains, as an accessory mineral in granites, and in various other igneous rocks.
anatases, various cuts - Brazil

Cut anatases, Minas Gerais, Brazil. Gem cutting by Afonso Marques. Photo by Eurico Zimbres. Licensed under CC By-SA 3.0.

What is Anatase?

Anatase, brookite, and rutile are polymorphous minerals. They share the same chemical formula, TiO2 (titanium dioxide), but have different crystal systems and other gemological properties.

Xanthitane is a soft, friable (crumbly), yellow-colored sphene (titanite) pseudomorph of anatase. Pseudomorphs are minerals that change chemistry without changing their crystal form. In this case, from TiO2 to CaTiSiO5.


Xanthitane, Jones Mine, Zirconia (Tuxedo Station), Henderson Co., North Carolina, USA, 2.5 x 1.9 x 0.7 cm. © Rob Lavinsky, Used with permission.

You might find references to anatase as “octahedrite.” The name comes from the “double pyramid” shape typical of many anatase crystals. However, despite this occasional appellation, anatases don’t form true octahedrons nor belong in the isometric crystal system.

anatase and rutile - Norway

A classic “double pyramid” anatase crystal covered with micro-rutiles. Matskorhae (Matskorhae), Odda, Hardangervidda, Hordaland, Norway. 1.5 x 0.5 x 0.5 cm. © Rob Lavinsky, Used with permission. (Image rotated).

Is Anatase a Good Jewelry Stone?

You’ll more likely find anatase in a mineral collection than a jewelry collection. Due to this gem’s perfect cleavage and hardness of 5.5 to 6, protective settings and occasional wear would be advisable for ring use. Jewelry such as pendants, brooches, and earrings would make excellent choices for this gem.

Transparent gems could display anatase’s birefringence and beautiful, high dispersion, which exceeds even that of diamond. However, transparent crystals tend to have darker colors, which can mask the gem’s dispersion. As jewelry stones, darker, opaque material might showcase its adamantine to metallic luster. Very dark faceted gems may appear unattractive.

Faceted anatase, Brazil (0.08 cts). Photo © Joel E. Arem, PhD, FGA. Used with permission.

Identifying Characteristics

Optical Properties

Anatase’s refractive indices (RI) vary extremely, depending on temperature and wavelength.

Some dark-colored crystals with small 2V may have biaxial optic character.

Transparent, faceted gems may show birefringent doubling.

How Can You Distinguish Anatases, Rutiles, and Brookites?

Of the three polymorphous titanium dioxide gems, anatase is the rarest.

You may encounter faceted rutile, especially synthetic rutile, more commonly than faceted anatase. The deeper color ranges of these two gems overlap, and they actually both have tetragonal crystal structures. However, rutile has a higher specific gravity (SG) and greater hardness. Rutile’s optical properties also differ. For example, it has a uniaxial (+) optic character.

Rare faceted brookites have some color overlap with anatases (but rarely blue) and share the same hardness. However, orthorhombic brookite has different optical properties, including a higher birefringence. It also has a higher SG.

Distinguishing Anatases from Other Similar Gemstones

Some more popular gemstones that share the same hardness and color range of anatases include transparent scapolites and opaque sodalites (blue). However, both these gems have luminescent properties, unlike anatases, as well as other distinguishing characteristics.

For more information on gem identification techniques, read “The Art and Science of Identifying Gemstones.”

oisanite - France

Before the official adoption of the name “anatase,” gems such as this were called oisanites, after the type locality, St Christophe-en-Oisans, Bourg d’Oisans, Isère, Rhône-Alpes, France. This beautiful topotype on matrix comes from the same deposit. Photo by Didier Descouens. Licensed under CC By-SA 4.0.

Are There Any Synthetic Anatases?

Anatase can act as a photocatalyst. For example, if exposed to light while underwater, anatase absorbs photons, which excites electrons in its atomic structure. In turn, these electrons split the water molecules into hydrogen and oxygen.


Anatase producing hydrogen gas out of water. Photo by O. Usher (UCL Mathematical and Physical Sciences). Licensed under CC By 3.0. (Cropped to show detail).

Since such a reaction has many possible applications, such as disinfecting water, cleaning oil spills, and creating solar cells, scientists have synthesized anatase, including crystal forms, for research purposes. However, there is no known jewelry use for this synthetic material.

Do Anatases Receive Gem Enhancements?

No known gem treatments.

Where is Anatase Found?

The Alpine regions of Switzerland produce gem material. Diamondiferous gravels in Brazil also yield gem-quality crystals.

Other notable crystal sources include the following locations:

  • United States: Arkansas; California; Gunnison County, Colorado; Massachusetts; North Carolina; Virginia.
  • United Kingdom: Cornwall; England; Wales.
  • France; Italy; Myanmar; Norway; Pakistan; Russia; Spain.
anatase - Switzerland

Anatase: Switzerland (0.5). © Joel E. Arem, PhD, FGA. Used with permission.

Stone Sizes

Exceedingly rare, faceted gems almost always weigh less than 1-2 carats. However, cut gems as large as approximately 6 carats are known.

Caring for Your Anatase Jewelry

Store anatases separately from harder gems to avoid contact scratches. Clean them with a soft brush, mild detergent, and warm water. For more care recommendations, consult our gemstone jewelry cleaning guide.

anatase - Spain

Anatase, Adra-Motril highway, Adra, Almería, Andalusia, Spain. Picture width 2 mm. Photo by Christian Rewitzer. Licensed under CC By-SA 3.0.

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