Garnet

What it actually is

A group rather than a species. Garnets are cubic silicates sharing the general formula X3Y2(SiO4)3, where different metals occupy the X and Y positions.

The main gem species are pyrope, deep red and magnesium-bearing; almandine, darker red with iron; spessartine, orange with manganese; grossular, which includes green tsavorite and orange hessonite; andradite, which includes the green demantoid; and uvarovite, a bright green that rarely occurs in cuttable sizes.

Most gem garnets are mixtures between these end members. Rhodolite is a pyrope-almandine mix with a purplish red. Malaia and colour-change garnets from East Africa shift between blue-green and purple under different light.

Hardness runs 6.5 to 7.5 depending on species, and garnet has no cleavage, which makes it durable.

Demantoid has higher dispersion than diamond, producing exceptional fire, and its horsetail inclusions of chrysotile are diagnostic of Russian material.

Where it comes from

India, Madagascar, Brazil, Tanzania, Kenya, Mozambique and Sri Lanka all produce garnet in quantity, and it is one of the more geographically widespread gems.

Bohemia, in what is now the Czech Republic, supplied pyrope for a nineteenth-century jewellery industry that produced the dense clustered Bohemian garnet pieces still found in antique shops.

Russia's Ural mountains produced demantoid from the 1860s, and Tiffany's George Kunz promoted it in the West.

Tsavorite was found in Tanzania in 1967 and named by Tiffany after Tsavo, and it is the most valuable common garnet.

Egyptian jewellery used garnet from at least 3000 BCE, and Anglo-Saxon and Merovingian goldsmiths set thin slices over patterned gold foil in cloisonné work, as at Sutton Hoo.

What the traditions claimed

The name comes from the Latin granatum, seed-bearing, after the pomegranate, whose seeds the small deep red crystals resemble. That connection did substantial work in the folklore, because the pomegranate is the fruit that binds Persephone to the underworld for part of each year, which suits a stone assigned to the darkest month.

Medieval lapidaries following Marbode credit garnet, often under the name carbuncle, with driving away sorrow and nightmares, and with glowing in the dark, a claim that recurs in many sources without any obvious basis.

Garnet was carried by travellers and by soldiers as a protective stone in several European traditions.

In Ayurvedic tradition, hessonite garnet is gomed, the gem of Rahu, the ascending lunar node, and it carries a specific and cautious prescriptive tradition of its own.

Garnet is January's birthstone in every list, one of the few completely uncontested assignments.

How it is worked with

This is one of the best gems anyone can own for practice and for wear. Hardness 7 with no cleavage, essentially untreated, inexpensive in its common red forms, and available everywhere.

The return reading is the useful one: garnet suits questions about coming back to something, whether that is a practice, a place or a person, rather than about starting fresh.

For anyone who wants a red stone that will survive a ring worn daily, this is the answer rather than ruby, at a fraction of the price.

Deep pyrope and almandine can look almost black in poor light because they absorb so much of it, so smaller stones and lighter cuts show the colour better than large deep ones.

Clean in warm soapy water. Garnet tolerates ultrasonic cleaning if it is free of fractures.

Buying it honestly

Garnet is one of the least treated gems in the trade, because heating and irradiation do little for it. That alone makes it a good purchase.

Composite doublets, with a thin garnet slice fused to coloured glass, were common in Victorian jewellery and still appear in antique pieces. Under magnification the join shows as a flat plane with trapped bubbles.

Red glass is sold as garnet at the very cheap end, and the temperature test separates them.

Synthetic garnets exist, notably YAG and GGG, but these are different compounds developed as diamond simulants rather than as garnet substitutes.

Demantoid and tsavorite are valuable enough to be worth faking, and green glass and synthetic green spinel appear. Russian demantoid's horsetail chrysotile inclusions are diagnostic and cannot be imitated.