Garnet

Most people picture garnet as a deep wine red. That is only the beginning. Garnet is a family of minerals that share one crystal structure and swap elements in and out as they grow, so the family runs from red and purple through orange and gold to vivid green.

Two of the most sought-after members come from Namibia. Green demantoid is mined in the Erongo region, and the bright orange spessartine the trade calls "mandarin garnet" was first found on the Kunene River, on our northern border.

Where the name comes from

The name comes from the medieval Latin granatus, "pomegranate", for the red seeds the gem resembles. Demantoid takes its name from the old German Demant, diamond, because the Russian miners who found it in the 1800s were struck by its fire.

Beliefs and legends

• For the afterlife. In ancient Egypt, pharaohs were buried with their red garnet necklaces, to take with them into the next life.
• King Solomon's stones. Under its old name, carbuncle, garnet was said to be one of the four precious stones God gave King Solomon.
• Favoured by clergy and nobles. In the Middle Ages red garnet was the gem of churchmen and the nobility.

The colours, and their names

• Red to purplish red (almandine, pyrope and the rose-purple rhodolite): the classic garnets.
• Orange (spessartine): the purest, brightest oranges are sold as mandarin garnet.
• Green (demantoid and tsavorite): demantoid is green andradite, known for its fire; tsavorite is green grossular, found in Tanzania and Kenya.
• Orangey brown to cinnamon (hessonite) and yellow-green (Mali garnet).
• Colour change and stars: a few garnets change colour between daylight and lamplight, and some show a star or a cat's eye.

Namibia's two garnets

Demantoid from the Erongo. The Green Dragon mine lies on Tubussis farm in the Erongo region. The deposit was found in the 1990s and has produced commercially since the mid-2000s. Only a little over a tenth of what comes out of the ground is good enough to cut, and most of it is cut into small stones of two to three millimetres. A clean one-carat Namibian demantoid is a rarity. The colours run from yellowish green to bluish green, and the golden greens are the most in demand.

Mandarin garnet from the Kunene. In the early 1990s bright orange spessartine was found in mica schist along the Kunene River, in the remote north-west where Namibia meets Angola. The deposit was soon worked out, but the name stayed: mandarin now means the purest orange spessartine, wherever it is found. Later finds came from Nigeria and Tanzania.

Treatments, honestly

Most garnets are sold exactly as they come from the ground. Fracture filling is used only rarely. Mandarin garnet is not normally treated. We have found no evidence that Namibian demantoid is treated, and we tell you what we know about each stone before you buy it.

How to judge a garnet

• Variety first. Demantoid and tsavorite are rare and are priced far above the common reds.
• Colour. In every variety, look for a lively, saturated colour. In mandarin garnet, the purer the orange, the higher the value.
• Clarity depends on the variety. Red garnets are usually clean to the eye; spessartine and hessonite often carry inclusions.
• Size. A large red garnet costs little more per carat than a small one, but demantoid and tsavorite climb steeply with size.

Caring for your garnet

Garnet is 6.5 to 7.5 on the Mohs scale: fine for pendants and earrings, and for rings worn with some care. Demantoid is at the softer end. Clean it in warm soapy water with a soft brush. Avoid steam, and avoid ultrasonic cleaning if a stone has fractures. Store it apart from harder gems such as diamond and sapphire.

At a glance

Mineral group	Garnet (a family of silicates)
Hardness	6.5 – 7.5 Mohs
Colours	Red, purple, orange, gold, brown, green; rarely colour change
From	Namibia (demantoid, Erongo; mandarin spessartine, Kunene); Tanzania, Kenya, Madagascar, Mali
Treatments	Usually none; rarely fracture filling. Disclosed per stone
Care	Warm soapy water, soft brush. No steam