The widespread availability of amethyst makes it one the most affordable of gemstones, although the quality of amethyst varies according to its source and region. A stone of the highest grade amethyst is extremely rare, so when one is found its value is determined by demand. Rarely will a top grade amethyst reach the value of the best sapphire or ruby.
The name originates from the ancient Greek word amethustos, meaning “not intoxicated”. In ancient times it was believed the stone was able to protect its owner from drunkenness. For this reason ancient Greek and Romans wore amethysts and used the stone to make drinking vessels. Powdered amethyst was often added to wine to prevent drunkenness.
Shades of Amethyst
The amethyst colour range is wide; from pale, almost colourless lilac to rich, deep violet. During the Victorian era pale amethysts were popular, and often called “Rose of France”. Russian amethysts mined in the Urals were celebrated for their magnificent rich colour, which shone brilliantly even under artificial light.
Gemmologists refer to the Four Cs of Connoisseurship when grading coloured gemstones. In order of importance these are: Colour, Cut, Clarity and Crystal. Colour considers a stone’s hue, saturation and tone. Cut describes the percentage of brilliance in the stone when viewed face up as well as its proportions - length, depth and width. Clarity defines a gemstone’s inclusions or flaws, which will add to a stone’s value when used for identification purposes. Inclusions are only called flaws when their presence negatively affects a gemstone’s beauty and durability. Crystal refers to the stone’s transparency; a good, well cut stone will appear to glow.
Amethyst Quartz
On Mohs’ Scale of Hardness the amethyst rates seven. Diamonds, the world’s hardest substance, are rated 10. While the amethyst’s weight and refraction are the same as other quartzes, its crystal structure is different. Because amethyst’s construction is stratified different layers and areas in a one piece of stone may display variations in colour intensity. This is the reason why there are few large cut amethysts displaying even dark colour, despite the fact it is found all over the world.
Until recently manganese was considered the source of the amethyst’s unique colour. Studies now indicate a combination of aluminium and iron, together with natural radioactive radiation are the reasons for the amethyst’s colour.
Amethyst and Heat
When exposed to a heat source an amethyst can change colour. At temperatures of around 250 degrees cloudy stones will transform and display a shining yellow to reddish brown colour. Clear amethysts with high transparency become pale yellow or even clear at temperatures of 400 degrees. Some amethysts are pale rose to almost colourless in daylight, and these can be re-coloured with radium radiation. Although the reason for this lack of colour is not known, the fact that amethysts can loose their colour means care should be taken to avoid exposing this jewellery to heat sources. Amethysts should not be worn while sunbathing or using a solarium. Sudden changes of temperature may also damage the stone.
Cuts of amethysts are grade using the terms Siberian (high), Uruguayan (medium) and Bahain (low), regardless of the region from where they were sourced. A brilliant round cut is often used to maximise the colour in a stone with irregular colour distribution in its crystals. Synthetic amethysts are difficult to differentiate from the genuine stone. Their chemical and physical properties are so similar only an expensive gemmological test will confirm a stone’s authenticity.
Amethyst Geography
Amethysts from South America are far larger in size than those from Africa, but the African stones offer a higher saturation in colour. Australian amethysts are also highly saturated.
The biggest amethyst-producing nations are Brazil and Uruguay, followed by Madagascar. Brazilian amethyst is lightly coloured, with hues ranging from pale to medium lilac. Stones from Uruguay present a medium to deeply saturated purple, but many of the stones are blemished. Bolivia and Argentina also produce good quality amethyst.
Madagascan amethysts contain dark red, violet colours. The southern African countries Namibia and Zimbabwe also contain amethysts, and Zambia produces around one thousand tonnes of amethyst every year. African amethysts are small, but renowned for their clarity and deep purple colour.
The world’s largest opencast amethyst vein is located in Maissau in Austria. Amethyst crystals from Italy and Germany are often large, with an even colouration of lighter purple hues. Quality amethyst is produced from rock cavities in granite rocks in Russia’s Ekaterinburg region. Mines in India, Sri Lanka and South Korea produce good quality amethyst gemstones.
Although there are many amethyst-producing sites in North America, the best jewellery stones are sourced from Arizona. Stones mined in North Carolina contain a rare bluish tint specific to that region. Canadian amethyst from Ontario is unique, presenting a reddish inclusion just below the surface of each crystal. Amethyst is considered the gemstone of Ontario.
Purple is traditionally the colour of royalty, and since the dawn of time amethysts have been used to adorn powerful monarchs and rulers. Today this beautiful gemstone is affordable and available to everyone in a range of cut and uncut stones.
For further information please see The Mythology of the Amethyst.
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