Carnelian, also known as Cornelian is an A grade agate, a variety of Chalcedony quartz, the crystals of these types of quartz are microscopic, other forms of Chalcedony quartz include Onyx and Jasper. The orange to red tones of Carnelian are due to iron oxides within the crystal. Most of today's Carnelian is heat treated to enhance the color. Crystal healers recommend Carnelian for memory and digestive issues. Carnelian was one of the twelve gems of Jerusalem.