Onyx is a cryptocrystalline form of quartz. The colours of its bands range from white to almost every colour, except shades such as purple and blue. Commonly, specimens of onyx available contain bands of colours of white, tan, and brown. Pure black onyx is the most famous variety and has a long history of use for hardstone carving and jewellery. Agate is a very fine grained form of Quartz. It grows within volcanic lava bubbles known as "geodes". Diamond saws are used to slice the Agate, it is then ground to remove any imperfections then polished and dyed to enhance and display the beautiful natural banding within. Most Agate comes from Brazil.