Pyrope garnet, 10.53 cts, 13.5 x 13.5 x 10 mm, Congo, “Concave Round Brilliant Cut” by Loren Brown. © RSA Gems. Used with permission.
Pyrope always occurs in series with other garnet species. Common, dark red garnets are a mixture of almandine and pyrope. Other mixtures also occur, in colors than can range from pale orange and pink to purple.
The International Gem Society (IGS) has a list of businesses offering gemstone appraisal services.
Large, clean pyropes of lively color are very rare and would be very expensive.
| Data | Value |
|---|---|
| Name | Pyrope Garnet |
| Is a Variety of | Garnet |
| Varieties | Chrome Pyrope |
| Crystallography | Isometric |
| Refractive Index | 1.73-1.766 |
| Colors | Red. Also, pale orange, pink, and purple “pastel” colors. Dark brown to black. |
| Luster | Vitreous |
| Hardness | 7-7.5 |
| Fracture | Conchoidal |
| Specific Gravity | 3.65-3.87 |
| Birefringence | None |
| Cleavage | None |
| Dispersion | 0.022 |
| Heat Sensitivity | Some |
| Luminescence | None |
| Luminescence Present | No |
| Transparency | Transparent to opaque |
| Absorption Spectrum | The chromium spectrum of emission lines in the far red is absent in pyrope; however, the almandine (iron) spectrum is often visible. Otherwise, Cr masks the almandine spectrum and we see a narrow, weak doublet at 6870/685O, with possible weak lines at 6710 and 6500. A broad band, about 1000 Å wide, may be visible at 5700. |
| Phenomena | Color change (rare) |
| Birthstone | January |
| Formula | Mg3Al2Si3O12 |
| Pleochroism | None |
| Optics | Isotropic. May show anomalous birefringence. |
| Etymology | Pyrope comes from a Greek word meaning “fire-like.” |
| Occurrence | In peridotites, kimberlites, and serpentine rocks, and sands and gravels derived from their weathering; also in eclogite and other basic igneous rocks. |
| Inclusions | Pyrope contains small rounded crystals, circular snowballs of quartz crystals, and (from Arizona) octahedra and minute needles. |
Pyrope crystal on matrix. Photo by Géry Parent. Public Domain.
Pure pyropes (end member in the series) are unknown in nature. The purest gem-quality specimen ever discovered contained about 83% pyrope, 15% almandine, and about 2% other garnets. (The purest non-gem quality specimen, discovered in the Dora Maira massif in the western Alps, contained 98% pyrope).
Pyropes always contain some almandine and spessartite components. The almandine component can easily be detected spectroscopically. Gems sold simply as “pyropes,” especially in large sizes, are usually almandines with a pyrope component.
GIA gemologists have examined pyropes with a dark brown to black color. These stones contained a slight admixture of andradite with black ilmenite inclusions.
Round pyrope-almandine garnet, 2.30 cts, Africa. Photo courtesy of liveauctioneers.com and Jasper52.
Chrome pyropes are popular stones with color that can rival rubies. In Arizona, ants have brought these gems to the surface, hence their nickname, “anthill garnets.” Although chrome pyropes have superb color, they have very dark tone.
Long known only from Arizona sources, chrome pyropes have also been found in Tanzania.
Round, brilliant-cut chrome pyrope, 2.41 cts, 8.1 mm, Tanzania. © The Gem Trader. Used with permission.
Some pyropes show an interesting color change. Material from Norway (N=1.747, SG=3.715) can show a wine red color in incandescent light and violet in daylight. However, these stones are very small (about half a carat).
Pyrope-spessartites (with some Ca and Ti) from the Umba Valley in Tanzania (N=1.757, SG=3.816) can show greenish blue color in daylight and magenta in tungsten light. They have inclusions of plates of hematite and rutile needles. All these color-change pyrope-spessartites have absorption bands at 4100, 4210, and 4300 that may merge to form a cutoff at 4350. In stones with a strong change of color, a band at 5730 is broad and strong.
Almandine-pyropes from Idaho can show a strong red to purplish red color shift under incandescent and LED light.
Pale pink to orange “pastel pyropes” from East Africa may show pink color in incandescent light and purple in fluorescent.
Another popular gemstone, malaia or malaya garnets may be pyrope-spessartites or even pyralspites — a blend of pyrope, almandine, and spessartite. Their colors range from red through shades of orange and brownish orange to peach and pink.
Purplish red rhodolite garnets are a blend of almandine and pyrope with small amounts of other garnet species. Rhodolites with higher spessartite content have lighter colors.
Rhodolite crystals, 7.95 and 6.96 cts, Lokirima, Lodwar, Turkana District, Rift Valley Province, Kenya. © Rob Lavinsky, www.iRocks.com. Used with permission.
Scientists have synthesized pyropes, both pure and in series with other garnet species, for research into their chemical and physical properties. You may rarely encounter lab-created pyropes in jewelry. (Note that pure pyropes would be colorless). However, you’re more likely to find simulants used in jewelry, lookalikes such as colored glass or cubic zirconia (CZ) or even other natural, red gemstones misidentified (or deliberately misrepresented) as pyropes.
Like most garnets, pyropes typically receive no treatments. However, in the 1970s, some almandine-pyropes were heated, adding a gray metallic sheen to their red color. Known as “Proteus garnets,” these are no longer commercially produced.
The area near Třebenice (Trebnitz), Czech Republic produces the best-known pyropes, the so-called Bohemian garnets, which occur in volcanic breccia, tuffs, and conglomerates. These garnets supported a major local industry in the 19th century. Today, production continues but on a smaller scale. An enormous quantity of pyrope from these mines has been sold over the years.
Earrings from a vintage suite of Bohemian garnet (pyrope) jewelry. Photo courtesy of liveauctioneers.com and Brunk Auctions.
South Africa produces pyropes with superb, blood red color but in small sizes. These garnets occur in kimberlite and eclogite associated with diamonds. Pyropes not only occur with diamonds but also sometimes form as crystal inclusions within diamonds.
Other notable gem-quality sources include the following localities:
A pyralspite garnet, a blend of pyrope, almandine, and spessartite, from Malawi. 4.81 cts, 1.7 x 9.1 x 6.9 mm. © RSA Gems. Used with permission.
Pyropes of large size are extremely rare. Faceted stones over 1-2 carats usually appear very dark.
The Kunsthistorisches Museum in Vienna holds many large pyropes. (There are stories about specimens the size of hen’s eggs in the former Imperial Treasury in Vienna).
The Green Vault in Dresden, Germany contain a huge pyrope said to be the size of a pigeon’s egg. Reports of a 468.5-ct gem also appear in the literature.
This opaque pyrope cabochon weighs a hefty 3,810.80 cts and measures 70.07 mm across. Photo courtesy of liveauctioneers.com and Pioneer Auction Gallery.
With no cleavage and a hardness of 7-7.5, pyropes make durable stones for any type of jewelry setting. However, take care when cleaning these gems. Inclusions may burst due to extreme heat or ultrasound and fracture the gem. Avoid mechanical cleaning systems and stick to a soft brush, mild detergent, and warm water, instead.
See our gemstone jewelry care guide for more recommendations.
14k yellow gold cocktail ring with 8 oval-cut pyropes surrounding pavé-set diamonds, 2.82 ctw. Photo courtesy of liveauctioneers.com and London Gallery Auctions.
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