Chrome Diopside

Chrome diopside is the bright green, gem-quality variety of diopside, a calcium magnesium silicate of the pyroxene group. Its intense green color comes from chromium, the same element that colors emerald and tsavorite garnet, giving it a rich, sometimes emerald-like appearance.

It is relatively affordable, offering a deep green color at a fraction of emerald's cost, though its modest hardness (5.5-6.5) and distinct cleavage make it more delicate. Stones are usually small, as larger sizes tend to look too dark.

The gem is sometimes marketed as "Siberian emerald" because of its color and primary source.

Diopside forms in metamorphic rocks such as marbles and skarns, and in certain ultramafic igneous rocks. Chrome diopside specifically crystallizes in chromium-rich environments, notably in kimberlites and peridotites in the deep mantle, where it is associated with diamond formation.

Because of this association, chrome diopside is used by geologists as an indicator mineral in diamond exploration. The main commercial gem source is the Inagli deposit in Yakutia (Sakha Republic), eastern Siberia, Russia. Additional occurrences are known in Pakistan, Myanmar, Italy, Finland, and parts of Africa.

Chrome diopside is identified by its vivid to dark green color, vitreous luster, hardness of 5.5-6.5, white-to-pale-green streak, and distinct cleavage in two directions. It is doubly refractive and can show pleochroism in shades of green.

Its specific gravity (~3.3) is moderate. Look-alikes include emerald (harder at 7.5-8, beryl), tsavorite and chrome tourmaline (harder), and green glass. The relatively low hardness, cleavage, and strong chromium green help distinguish chrome diopside, while gemological testing confirms the pyroxene identity.

Chrome diopside is used mainly as a faceted gemstone in earrings, pendants, and necklaces, valued as an affordable rich-green alternative to emerald and tsavorite. Because it is soft and cleavable, it is best kept out of rough daily-wear rings or set protectively.

The mineral diopside also serves as an indicator in diamond prospecting. Metaphysically, chrome diopside is associated with the heart, growth, and renewal. Value depends on a bright, not-too-dark green and good clarity; very small stones often show the most attractive color since larger ones can appear nearly black.