Star Diopside

Diopside is a calcium-magnesium-silicate and one of the most common minerals of the pyroxene-group. It forms two complete series with Hedenbergite and Johannsenite.

The 4-rayed star is caused by reflection of light at needle-shaped inclusions of magnetite. It is only visible under single light in gems with a domed surface (cabochons, spheres, beads) (see asterism)

Star Diopside shop

sterndiopsid star diopside

Origin of name: from Greek δίς dis meaning double, ὄψις opsis meaning sight or vision and ἰδού idos meaning shape. One interpretation says, this hints to the fact that Diopsides often appear as twinned crystals. According to another view, it alludes to the two possible orientations of the prism faces of Diopside crystals.

Synonyms and trade names: particularly in India Star Diopside is very often offered as "Black Star". This is misleading, as the name "Black Star" must, in accordance with trade practices, only be used for black Star Sapphires. With all other black star stones, like black Star Moonstone, the mineral name must be added.

Can be confused with: the 4-rayed star of Star Diopside has a diagnostic feature, which, at least in theory, should render it unmistakable. One ray is significantly sharper than the other.
In very rare instances brownish-grey, rather than black or dark grey, Star Diopsides
are found, which could be confused with the equally rare Star Bronzite. However, in Star Bronzite both rays are of equal sharpness.

Localities: almost all of the Star Diopside comes from India. The most important deposits are in the states of Uttar Pradesh, Andhra Pradesh, Rajasthan and Karnataka.
Burma (Myanmar) is another known locality.

Handling:  as a ringstone Star Diopside must be worn with care as it will rather quickly lose its polish when worn daily.
Regarding Diopside´s susceptibility to heat, acids and brines we have contradictory reports. Goldsmiths told us that all contact with boric acid and galvanic baths must be avoided and that Diopside should not be cleaned ultrasonically.
However, the German Wikipedia entry states, that it is virtually unsusceptible to all acids except hydrofluoric acid.

To all goldsmiths, setters and gem cutters out there: if you have any working experience with (Star) Diopside, please let us know.

Diopside shows distinct cleavage. Apply pressure carefulle during setting.

Star Diopside shop

Gemmological Properties of Star Diopside

CaMg [Si2O6]
Crystal system:
Mohs hardness:
5.5 - 6.5
Specific gravity:
3.22 - 3.78
Refractive index:
1.663 - 1.728
Max. Birefringence:
vitreous, dull
conchoidal, brittle
black, dark grey, rare brownish grey