Pyrope Garnet

The blood-red color of pyrope garnet is due to its iron and chromium content. It rarely has inclusions, but when present they are rounded crystals or have irregular outlines. As with all garnets, pyrope has no cleavage, and fracture is subconchoidal to uneven.
Pyrope garnet is found in volcanic rock and alluvial deposits, and may, along with certain other minerals, indicate the presence of diamond-bearing rocks. Localities include Arizona (USA), South Africa, Argentina, Australia, Brazil, Burma, Scotland, Switzerland, and Tanzania.
Pyrope comes from the Greek pyrops, meaning fiery. Swiss and South African pyropes are lighter red than stones from Bohemia, where pyrope jewelry has been made for over 500 years.
Perfectly transparent, clear, uniformly colored crystals of pyrope garnet were popular for jewellery in the 18th and 19th centuries.

Properties

Chemical Composition: 

Magnesium Aluminium Silicate - Mg₃Al₂(SiO₄)₃

Colors / Varieties: 

• Colorless (pure), red, slightly orange-red, violet-red in darker tones. High intensities common in the red hue.
• Four ray star pyrope.

Hardness: 

7.25

Specific Gravity: 

Pure: 3.582; Range: 3.65 - 3.80

Refractive Index / Birefringence: 

Pure: 1.714; Range: 1.720 - 1.740

Dispersion: 

0.027

Magnification: 

Crystals and needles are present.

U.V. Fluorescence: 

Inert

Spectrum: 

• Iron rich: 575nm, 527nm, 505nm
• Chrome rich: strong diagnostic band between 520nm and 620nm; doublet of moderate strength at 687nm and 685nm and weak lines at 671nm and 650nm.

Cause of Color: 

Chromium, Iron

Treatment (Enhancement): 

-

Specific Tests & Remarks: 

-

Simulants (with key separation tests): 

Rhodolite (R.I., S.G., spectrum), Red Spinel (spectrum, U.V. fluorescence, inclusions), Almandine Garnet (R.I., S.G., spectrum), Tourmaline (optic character, spectrum), Glass (spectrum, U.V. fluorescence, inclusions), Synthetic Cubic Zirconia (R.I., S.G., dispersion, lustre), etc.

Sources: 

Bohemia, South Africa, U.S.A. (Arizona), Sri Lanka, Madagascar

Cuts & Uses: 

Facetted, cabochon, beads, carvings, etc.