A natural gem, of a violet colour and great brilliancy, as hard as the ruby or sapphire, from which some say it only differs in colour. The Asiatic are of a deep purple hue, and are deemed the most valuable. The German are violet. Some amethysts are, however, made colourless by art, when they are often mistaken for diamonds; the superior hardness of the latter will, however, enable any person to detect the imitation.