Quartz is one of the most abundant minerals on Earth and can be found in large crystals, sometimes measuring many feet in length. Most Quartz however, cannot be regarded as a gem as it is neither rare nor beautiful.
The term Rock Crystal is often used to describe colourless Quartz, which for many centuries has been used to create such items as crystal balls.
Ancient Romans believed that Rock Crystal was formed by gods who were able to permanently freeze ice. It is often formed in igneous and metamorphic rocks; however smaller, finer quality Rock Crystals are discovered in geodes and pegmatites.
Rock Crystal should not be confused with “lead crystal glass”. Rock Crystal is made by Mother Nature, whereas lead crystal glass is man- made. With lead crystal, lead oxide is added to the molten glass, which dramatically increases the refractive index of the glass, giving it a greater sparkle. For example, Swarovski - the famous producers of jewellery and sculptures - is believed to add approximately 32% lead in their manufacturing process, in order to produce items that demonstrate maximum brilliance.
Although natural Rock Crystals can be found worldwide, some of the better quality samples, those regarded as gem-quality, are located in the UK, Switzerland, Madagascar and Brazil.