Hessonite

Hessonite is the variety of grossular, the calcium–aluminium garnet, that ranges from yellowish orange to reddish orange and reddish brown; its colour has earned it the name “cinnamon stone”. It owes its colour to traces of manganese and iron. Inside, it often shows a swirling look like whisky poured into water, which helps to identify it. Its main sources are Sri Lanka, India, Canada and Tanzania. It is relatively inexpensive and easy to find, and in India it is known as “gomed”, the stone that stands for Rahu in nine-gem Navaratna jewellery.

Jewellery: it is set in rings, earrings and necklaces, especially in warm, earth-toned jewellery. Being inexpensive and easy to find makes it an attractive choice among orange garnets. Carvings and cameos: it has long been used for engraved gems, and museums hold cameos carved from hessonite. Traditional jewellery: in India it is one of the nine stones of Navaratna jewellery. Collecting: well-formed crystals from the Alpine valleys of Italy and from Canada are sought by collectors.

It has a hardness of 6.5–7 on the Mohs scale. It scratches glass and steel; a steel knife cannot scratch it. Its specific gravity is 3.64–3.69 g/cm³.

Its best-known localities: Sri Lanka's gem gravels (Ratnapura area); Jeffrey mine, Asbestos (Val-des-Sources), Quebec, Canada; India; Tanzania; Ala valley, Piedmont, Italy.

Its colour ranges from honey yellow through orange to reddish orange and reddish brown, sometimes with a pinkish tone. Under a loupe it often shows a swirling, hazy look, like whisky mixing into water or air shimmering in a heat wave. Small crystal inclusions such as apatite, calcite, diopside and zircon may also be present. It is easily told from zircon, which it resembles, by specific gravity: 3.64–3.69 for hessonite against about 4.6 for zircon. Its refractive index is about 1.73–1.76. Dyed glass, plastic and synthetic quartz: these may be sold as “hessonite” or “gomed”, especially online.

On the “street to diamond” value ladder it sits on step 5 of nine: Ornamental stone. Hessonite is a relatively inexpensive, readily available garnet; its value depends mostly on the liveliness of its colour, its clarity and its size. Saturated, bright orange and reddish-orange stones are more sought after than pale or brownish ones. The swirling “whisky” look inside is a natural feature of this stone, but when it makes the stone very hazy, brilliance and value fall. Treatments such as fracture filling must be disclosed, and “gomed” stones sold for their beliefs call for care, because glass and plastic imitations are common.

In the nine-gem Navaratna jewellery of Hindu tradition, hessonite (gomed) stands for Rahu, the ascending node of the Moon. Sellers of gems for Indian astrology claim that wearing gomed removes the “harmful effects” of Rahu, reduces obstacles and delays in life and brings career success. The same sources claim that gomed eases mental stress and confusion, and even that it helps against depression. There is no scientific evidence that hessonite has any astrological effect, removes obstacles, or relieves stress or depression; depression is an illness that needs treatment, so see a doctor. Because stones with high belief value attract imitation, many stones sold for this purpose may be glass or plastic. This section reports beliefs; it is not health information. There is no scientific evidence for these claims and no stone replaces medical treatment.