Ruby is a red gemstone. It's colour is mainly through its chromium content. Ruby is a variety of the mineral corundum (aluminium oxide).
We have two sizes of rough ruby. The small is approximately 1.5-2.5cm across the widest points. The medium is approximately 2.5cm -3.5cm across the widest points. They are mainly hexagonal but as they are rough, they do not form perfect hexagonal shapes. Some are deeper than others and slightly less regular.