Green Amethyst online. Green amethyst does not occur naturally. It is produced by heating amethyst or yellowish quartz. However, not all amethyst or yellow quartz can be heated to produce prasiolite. According to gemological sources, only quartz from the Montezuma deposit in Minas Gerais, Brazil, can be heated to produce prasiolite. Amethyst or yellowish quartz is heated to about 500 degrees centigrade to produce the leek-green color. Unfortunately, the colour is known to fade when exposed to strong sunlight.
Some so-called ‘green amethyst’ on the market is actually synthetic quartz produced by the hydrothermal method. It is usually found in a vivid mint-green or blue-green rather than the paler golden-green of prasiolite. The unnatural color is usually a sure sign that it is synthetic.