Diopside Value, Price, and Jewelry Information

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DIOPSIDE: New York (2.15), Kenya (0.75, chrome diopside), USSR (3.5, chrome diopside). Photo © Joel E. Arem, PhD, FGA. Used with permission.

Diopside Value

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Diopside Information

Data	Value
Name	Diopside
Varieties	Chrome-Diopside, Lavrovite, Violane
Crystallography	Monoclinic. Crystals often well formed, prismatic, stubby, also massive.
Refractive Index	Varies by series members, 1.664-1.751
Colors	Colorless, white, gray, pale green, dark green, blackish green, brown, yellowish to reddish brown, bright green (Cr variety); rarely blue. Schefferite is light to dark brown. Hedenbergite always dark green, brownish green, or black.
Luster	Vitreous.
Polish Luster	Vitreous to resinous
Fracture Luster	Vitreous to resinous.
Hardness	5.5 - 6.5
Wearability	Poor
Fracture	Conchoidal to uneven
Specific Gravity	Usually 3.29; range 3.22-3.38 for diopsde, higher if more Fe present.
Birefringence	Varies by series members, 0.024-0.032. See "Identifying Characteristics" below.
Cleavage	Perfect 1 direction
Dispersion	0.017-0.020
Stone Sizes	New York material provides cutting rough of fine quality and large size. The Italian, Swiss, and Austrian diopsides are usually smaller but of fine color. Diopside from Madagascar is very dark green and less attractive, up to about 20 carats. Chrome diopsides are known up to about 10-15 carats. Most diopside localities provide material that cuts 2-10 carat gems. American Museum of Natural History (New York): 38.0 (green, New York). Smithsonian Institution (Washington, D.C): 133.0 (black, star, India); 24.1 (black, catseye, India); 19.2 (green, Madagascar); 6.8 (yellow, Italy); 4.6 (yellow, Burma).
Heat Sensitivity	No
Luminescence	Blue or cream white in SW, also orange yellow; sometimes mauve in LW. May phosphoresce a peach color.
Luminescence Present	Yes
Luminescence Type	Fluorescent, Phosphorescent, UV-Long, UV-Short
Enhancements	None known.
Transparency	Transparent to Opaque
UV Long	green, mauve
UV Short	inert, blue/white, slightly yellowish/white, orange/yellow. May phosphoresce peach.
Absorption Spectrum	Lines at 446, 493 and 505 nm. Chrome diopside, sharp lines at 490, 505, 508 nm, indistinct lines at 635, 655, 670 and double line at 690 nm. Chrome diopside has lines at 5080, 5050, 4900, plus fuzzy bands at 6350, 6550, 6700 and a doublet at 6900. Pale green diopside gives lines at 5050, 4930, and 4460.
Phenomena	Asterism, (usually 4 ray, occasionally 6) Chatoyancy
Formula	CaMgSi₂O₆. Complete series to CaMgSi₂O₆ = Hedenbergite Intermediate members = Salite, Ferrosalite Ferrosalite rich in Mn and Zn = Jeffersonite Diopside rich in Mn = Schefferite Diopside rich in Mn and Zn = Zinc Schefferite (variety) Diopside rich in Cr = Chrome Diopside (variety) Diopside color varieties include baikalite. alalite and malacolite (Pale green) and violane (purple).
Pleochroism	Diopside: none Jeffersonite: dark brown/light brown Schefferite: dark brown/light brown Hedenbergite: pale green/green brown Chrome Diopside: yellow/green Salite: pale green/blue-green/yellow-green
Optics	Biaxial (+). See "Identifying Characteristics" below.
Optic Sign	Biaxial +

Identifying Characteristics

Intermediate compositions have intermediate properties in the diopside-hedenbergite series; increasing iron content results in higher properties. The pleochroism of salite is: pale green/blue-green/yellow-green.

	Diopside	Hendenbergite	Jeffersonite	Schefferite	Chrome Diopside
Optics
a	1.664- 1.695	1.716 -1.726	1.713	1.676	1.668-1.674
β	1.672 – 1.701	1.723 – 1.730	1.722	1.683	1.680
γ	1.695 – 1.721	1.741 -1.751	1.745	1.705	1.698-1.702
2V	50-60°	52-62°	74°	60°	55°
Density	3.22-3.38	3.50 -3.56	3.55	3.39	3.17-3.32
Birefringence	0.024-0.031	0.025-0.029	0.032	0.031	0.028
Pleochroism	none	pale green / green-brown	dark/light brown	dark/light brown	yellow/green

Occurrence: in Ca-rich metamorphic rocks; in kimberlite (Cr-diopside).

Burma: yellow faceted gems; also catseyes and pale green faceting material.

Madagascar: very dark green cutting material. Sri Lanka: cuttable pebbles.

Ontario, Canada: green faceting material.

Quebec, Canada: red-brown material that cuts gems to 2 carats.

Ala, Piedmont, Italy: fine green diopside (alalite is local name).

St. Marcel, Piedmont, Italy: violet variety of diopside (violane).

Zillerthal. Austria: fine green crystals, some transparent.

Georgetown, California: green diopside. Crestmore, California: large crystals (non-gem).

DeKalb, New York: fine transparent green crystals up to several inches in length.

Slyudyanka, USSR: green crystals (baikalite or malacolite); and chrome diopside.

Outokumpu, Finland: fine deep green Cr-diopside.

Nammakal, India: star stones and catseyes, also dark green facetable material.

Franklin, New Jersey: jeffersonite, schefferite, and Zn-schefterite

Långban, Sweden: jeffersonite, schefferite, and Zn-schefferite.

Kenya: chrome diopside.

Comments: Violane has been used for beads and inlay—transparent material is always very tiny. The color of this material is deep violet or blue and is very rare. Catseye material cuts extremely sharp eyes, the best being from Burma. Faceted diopside is not extremely rare, but large (over 15 carats) clean stones are. Colors are usually dark, so a bright and attractive gem is most desirable. Hedenbergite and the intermediate varieties tend always to be opaque except in very thin splinters. Chrome diopside, quite rare in sizes over 3-4 carats, has become available in commercial quantities from the USSR. The color is excellent, with Cr content about 0.5% by weight.

Name: Greek words meaning appearing double.

Variety Names:

Diopside, (CaMgSi2O6) runs in a solid-state series to hedenbergite, (CaFeSi2O6)

Salite, Ferrosalite, intermediates between diopside and hedenbergite.

Jeffersonite is ferrosalite plus Mn and Zn

Schefferite is diopside plus Mn

Zinc Schefferite is diopside plus Mn and Zn

Also:

Alalite, colorless to light green

Cats Eye diopside

Chrome diopside, deep green coloring from chromium, usually transparent

Malacolite, light colored, translucent stones.