The Navratna gemstone of Mangal, the Mars
Moonga is the gemstone of Mangal, or Mars, and like the pearl it is organic rather than mineral. Italian Mediterranean coral and Japanese coral are the two origins most sought after in India, the first for its even oxblood tone and the second for a brighter orange red.
In Vedic tradition Moonga is worn to support Mars, and is associated with courage, drive and physical stamina.
Written by Kamal Kishore Agarwal, founder and gemmologist, who holds a Gem-A Diploma in Gemmology with Merit and has selected stones in Johari Bazaar since 2008.
Dyed and reconstituted coral is common and difficult to spot by eye. Buy only against a report that confirms the material is natural and states whether it has been dyed or stabilised. Untreated coral of good colour is genuinely scarce, and a price that looks too easy usually is.
Red coral is not a mineral. It is the skeleton of a colony of marine animals, laid down as calcium carbonate over decades, which is what makes it one of only two organic materials among the nine Navratna stones. Mediterranean Corallium rubrum, traded as Italian coral, is the classic Moonga material and runs to a deep even ox-blood; Pacific and Japanese species reach comparable colours with a different structure.
Dyed coral is the substitution to expect, and it comes in two forms. Cheap pale coral of a different species, often bamboo coral, is dyed red and sold as Italian or Japanese material. Separately, white howlite and magnesite, both soft porous minerals, take dye readily and are sold as coral outright. Reconstituted coral is powdered genuine coral bound with resin and pressed into shape, which is not quite an imitation and not quite the real thing, and it should be disclosed. Gilson created a synthetic coral in the 1970s that is still traded. Plastic and glass account for most of what is sold to tourists. In every case the test is the same: look for structure, since natural coral has fine parallel striations along its length and concentric growth rings across a cut end, and none of the substitutes has both.
Dyed coral and reconstituted coral, which is powdered coral bound with resin and pressed, are both widespread and both much cheaper than the real thing. Look along the surface for the fine parallel longitudinal striations natural coral carries, and look into any drill hole or fissure for colour pooling more strongly there than on the surface, which is what dye does. Reconstituted material tends to an unnaturally uniform colour with no structure visible at all.
Coral is light, with a specific gravity around 2.65 against corundum’s 4.0, so a given weight of coral covers far more area than the same weight of ruby or sapphire. A prescribed ratti in Moonga therefore produces a physically large piece, which is worth knowing before you commission a mount for it. Coral is also among the least expensive of the nine per carat, so weight is rarely the binding constraint. What costs money is colour: an even, untreated, deep oxblood with no white showing is genuinely scarce, and that is where a Moonga budget is best spent.
Coral is soft, roughly 3 to 4 on the Mohs scale, and being calcium carbonate it is attacked by acid, including perfume, vinegar and sweat. Put it on last and take it off first, wipe it with a soft damp cloth, and never let it near an ultrasonic cleaner or a household cleaning product.
As practised in Vedic tradition. Your astrologer’s instruction takes precedence over any general rule.
2 stones in the shop today, with the weight and treatment of each stated below and the laboratory named wherever a report is held.
