Throughout history, quartz has been the chameleon gemstone, imitating many expensive gemstones. A transparent purple quartz which is the most important quartz variety used in jewellery. Quartz has been an important crystal in history primarily because it is extremely useful in industrial and commercial applications. It was the first crystal used in radio transmission and reception and was essential in the development of computers. Click here for the full article. Amethyst complete- February birthstone