The commonest type of crystalline alumina, α-aluminium oxide, is called corundum. When trace factors help it become surface crimson it is known as ruby, but all other colorations slide underneath the designation sapphire. Corundum contains a trigonal Bravais lattice with an area team of R-3c (number 167 from the International https://michelangeloq529cgj0.empirewiki.com/user