In the Middle Ages, it was considered a symbol of royalty and used to decorate English regalia. In the Old World, amethyst was considered one of the Cardinal gems, in that it was one of the five gemstones considered precious above all others, until large deposits were found in Brazil. Value
Until the 18th century, amethyst was included in the cardinal, or most valuable, gemstones (along with diamond, sapphire, ruby, and emerald), but since the discovery of extensive deposits in locations such as Brazil, it has lost most of its value. It is now considered a semiprecious stone.Collectors look for depth of color; possibly with red flashes if cut conventionally. As amethyst is readily available in large structures, the value of the gem is not primarily defined by carat weight. This is different from most gemstones, since the carat weight typically exponentially increases the value of the stone. The biggest factor in the value of amethyst is the color displayed.The highest-grade amethyst (called "Deep Russian") is exceptionally rare. When one is found, its value is dependent on the demand of collectors. The highest-grade sapphires or rubies are still orders of magnitude more expensive than amethyst. Handling and care
The most suitable setting for gem amethyst is a prong or a bezel setting. The channel method must be used with caution.Amethyst has a good hardness, and handling it with proper care will prevent any damage to the stone. Amethyst is sensitive to strong heat and may lose or change its colour when exposed to prolonged heat or light.
A grading system has been developed to categorize the degree of skin involvement:
Acute papular onchodermatitis – scattered pruritic papules
Chronic papular onchodermatitis – larger papules, resulting in hyperpigmentation
Lichenified onchodermatitis – hyperpigmented papules and plaques, with edema, lymphadenopathy, pruritus and common secondary bacterial infections
Skin atrophy – loss of elasticity, the skin resembles tissue paper, lizard skin appearance
Depigmentation – leopard skin appearance, usually on anterior lower leg
Glaucoma effect – eyes malfunction, begin to see shadows or nothingOcular involvement provides the common name associated with onchocerciasis, river blindness, and may involve any part of the eye from conjunctiva and cornea to uvea and posterior segment, including the retina and optic nerve. The microfilariae migrate to the surface of the cornea. Punctate keratitis occurs in the infected area. This clears up as the inflammation subsides. However, if the infection is chronic, sclerosing keratitis can occur, making the affected area become opaque. Over time, the entire cornea may become opaque, thus leading to blindness. Some evidence suggests the effect on the cornea is caused by an immune response to bacteria present in the worms.The infected persons skin is itchy, with severe rashes permanently damaging patches of skin. Mazzotti reaction
The Mazzotti reaction, first described in 1948, is a symptom complex seen in patients after undergoing treatment of onchocerciasis with the medication diethylcarbamazine (DEC). Mazzotti reactions can be life-threatening, and are characterized by fever, urticaria, swollen and tender lymph nodes, tachycardia, hypotension, arthralgias, oedema, and abdominal pain that occur within seven days of treatment of microfilariasis.