Quartz comes in a variety of colours, each having their own name such as Clear, Purple (Amethyst), Golden-Yellow (Citrine), Yellow (Lemon Quartz), Golden-Green (Oro-Verde), Green (Prasiolite), Brown and Black (Smokey Quartz) as well as several hues of Red or Yellowish-Red etc (eg: Madeira Citrine). While most are natural colours, some are the product of Natural or Lab Irradiation or Heat Treatments.