Diopside pair 1.83 ct
Weight: 1.83 ct
Shape: Rectangle Cushion
Dimension: 7.0 x 5.0 x 3.0 mm
Color Saturation: High
Treatment: No indication of treatment
Diopside is a monoclinic pyroxene mineral with composition MgCaSi2O6. It forms complete solid solution series with hedenbergite (FeCaSi2O6) and augite, and partial solid solutions with orthopyroxene and pigeonite. It forms variably colored, but typically dull green crystals in the monoclinic prismatic class. It has two distinct prismatic cleavages at 87 and 93° typical of the pyroxene series. It has a Mohs hardness of six, a Vickers hardness of 7.7 GPa at a load of 0.98 N, and a specific gravity of 3.25 to 3.55. It is transparent to translucent with indices of refraction of nα=1.663–1.699, nβ=1.671–1.705, and nγ=1.693–1.728. The optic angle is 58° to 63°.
Diopside is found in ultramafic (kimberlite and peridotite) igneous rocks, and diopside-rich augite is common in mafic rocks, such as olivine basalt and andesite. Diopside is also found in a variety of metamorphic rocks, such as in contact metamorphosed skarns developed from high silica dolomites. It is an important mineral in the Earth’s mantle and is common in peridotite xenoliths erupted in kimberlite and alkali basalt.
Gemstone quality diopside is found in two forms: the black star diopside and the chrome diopside (which includes chromium, giving it a rich green color). At 5.5–6.5 on the Mohs scale, chrome diopside is relatively soft to scratch. Due to the deep green color of the gem, they are sometimes referred to as Siberian emeralds, though they are on a mineralogical level completely unrelated, emerald being a precious stone and diopside being a semi-precious stone.
Crystal system: Monoclinic
Mohs scale hardness: 5.5 – 6.5
Luster: Vitreous to dull
Specific gravity: 3.278
Optical properties: Biaxial (+)
Refractive index: nα= 1.663 – 1.699, nβ= 1.671 – 1.705, nγ= 1.693 – 1.728
Dispersion: Weak to distinct, r>v
Melting point: 1391 °C