Amethyst is a violet variety of quartz often used in jewelry.
the name from the Koine Greek "intoxicate", a reference to the relief that the stone protect its owner from drunkneness. the ancient Greeks wore amethyst and made drinking vessels decorated with it in the belief that it would prevent intoxication. it's one of the several forms of quartz. Amethyst is a semiprecious stone is the traditional birthstone for February. Amethyst occurs in ptimary hues from a light pinkish violet to a deep purple. Amethyst may rexhibit one or both secondary hues, red and blue. the best varieties of amethyst can found in Siberia Sri Lanka, Brazil, and the far East. the ideal grade is called "deep Siberian" and has a primary purple hue of around 75%-80%, with 15%-20% blue and(depending on the light source) red secondary hues. green quartz is sometimes incorrectly called green amethyst, which is a misnomer and not an appropriate name for the material, the proper terminology being prosiolite. other names for green quartz are vermarine or lime citrine . of very instensity, the color of amethyst is often laid out in stripes parallel to the final faces of the crystal. one aspect in the art of lapidary involves correctly cutting the stone to place the color in a way that makesthe tone of the finished gem homogeneous. Often, the fact that sometimes only a thin surface layer of violet color is present in the stone or that the color is not homogeneous makes for a difficult cutting. the color of amethyst has been demonstrated to result from substitution by irradiation of trivalent iron( Fe) for silicon in the structure, in the presence of trace elements of large ionic radius, and to a certain extent, the amethyst color can naturally result from displacement of transition elements even if the iron concentration is low. Natural amethyst is dichroic in reddish violet and blueish violet, but when heated, turns yellow-orange,yellow-brown or dark brownish and may resemble citrine, but loses its dichroism unlike geniune citrine. when partically heated, amethyst can result in ametrine. amethyst can fade in tone if overexposed to light sources and can be artificially darkened with adequate variety quartz (SiO) and owes its violet color to irradiation, iron impurities(in some cases in conjunction with transition element impurities) and the presence trace elements, which result in complex crystal lattice substitutions. the hardness of the mineral is the same as quartz, thus it is suitable for use in jewelry.