Hessonite

History and lore

Hessonite is the warm orange to cinnamon-brown variety of grossular garnet, and in South Asia it is known above all by its Sanskrit name, gomeda (Hindi gomed), the gem of the shadow planet Rahu. The Sanskrit name is usually explained as describing its honey- or ghee-like colour. The European name is less flattering: it comes from the Greek hēssōn, "lesser", because the stone is slightly softer and lighter than most other garnets. English gem books also called it "cinnamon stone", and the European trade long sold it as "hyacinth" or "jacinth", names it shared with orange zircon, so a hyacinth in an old inventory or lapidary may be either stone.

Indian gem literature, the ratnaśāstra tradition, treats gomeda as one of the recognised precious stones. Texts such as the Ratnaparīkṣā attributed to Buddhabhaṭṭa and the gem chapters of the Garuḍa Purāṇa, both difficult to date precisely, tell how gems arose from the body of the asura Bala after his sacrifice, and explain how to judge each stone's colour, lustre and flaws. The French scholar Louis Finot gathered several of these texts in Les lapidaires indiens (1896).

In the traditions

Hessonite's religious importance comes from the Navaratna, the "nine gems" that correspond to the nine grahas of Indian astrology: ruby for the Sun, pearl for the Moon, red coral for Mars, emerald for Mercury, yellow sapphire for Jupiter, diamond for Venus, blue sapphire for Saturn, hessonite for Rahu and chrysoberyl cat's eye for Ketu. In the classic Navaratna jewel the ruby sits at the centre and the other eight surround it by direction, with hessonite usually in the south-western place assigned to Rahu.

Rahu himself comes from the Puranic story of the churning of the ocean. When gods and asuras churned the milk ocean for amrita, the nectar of immortality, an asura slipped among the gods to drink it; the Sun and Moon exposed him, and Vishnu cut off his head before the nectar passed his throat. The immortal head became Rahu and the body Ketu, and Rahu's periodic swallowing of the Sun and Moon explains eclipses. In Jyotisha Rahu is the ascending lunar node, a shadowy graha associated with ambition, obsession, foreign things and sudden reversals. Astrologers in this tradition may recommend gomed when Rahu is judged prominent in a chart or during its eighteen-year major period (mahādaśā); modern manuals commonly describe setting it in silver or a five-metal alloy and wearing it on the middle finger, though the details differ from one astrologer to another. The nine-gem idea travelled with Indian culture into Southeast Asia, where it shaped royal regalia such as Thailand's Order of the Nine Gems. For the wider system, see Vedic astrology.

Meaning and symbolism

Within Jyotisha the stone's meaning is defined by Rahu: it is worn to steady the confusion, fear and restlessness Rahu is said to bring, and to turn its hunger for success into clear purpose. Because Rahu is also linked with poisons, deceit and hidden enemies, gomed has a protective reputation. Western crystal books, which took the stone up in the late twentieth century, describe it as grounding and as a stone of self-respect, meanings drawn partly from the wider garnet family. Scientific studies have not found that wearing a gemstone changes a person's fortune or health; these recommendations belong to the astrological tradition.

The mineral

Hessonite is a calcium-aluminium garnet whose colour comes from small amounts of iron and manganese. It forms in metamorphosed limestones and skarns, and much gem material is washed from gravels. Sri Lanka, especially the gem gravels around Ratnapura, has long been the classic source; India, Tanzania, Madagascar and Canada also produce it. At 7 to 7.5 on the Mohs scale it is durable enough for rings.

Under a loupe hessonite often shows a distinctive swirling "treacle" or heat-wave texture and small rounded crystal inclusions, which help gemmologists separate it from orange zircon, spessartine garnet, citrine and glass, all of which are sometimes sold as gomed. For an expensive stone, ask for a laboratory report. Clean it with warm soapy water and a soft brush, and store it apart from harder gems.

Sources and further reading

• Les lapidaires indiens — Louis Finot, 1896
• The Curious Lore of Precious Stones — George Frederick Kunz, 1913
• Gems: Their Sources, Descriptions and Identification — Robert Webster, 1962
• Gemstones of the World — Walter Schumann, 1977