When look at the texture of carnelian, it belongs to chalcedony texture, the same as crystal which belongs to silicon dioxide (SiO2), but its crystal belongs to micro-crystal in hidden crystal type, it has different colours like white, blue, green, brown, black and red etc..., among them red colour type is called carnelian. Western scholars think that carnelian dZi has over 5,300 years of history, the currency of Mesopotamia people is made by applying a chemical colourings on top of the bead and put under high temperature, that's why it is called etched carnelian, and list it as a member of the dZi family. There is quite a lot of inherited carnelian dZi, but those over 30 mm are rare.
