The most common type of crystalline alumina, α-aluminium oxide, is named corundum. When trace elements enable it to be seem crimson it is referred to as ruby, but all other colorations fall underneath the designation sapphire. Corundum incorporates a trigonal Bravais lattice with an area team of R-3c (range 167 https://trevorhkmrt.blogripley.com/35569178/everything-about-diamond-paste