The most common sort of crystalline alumina, α-aluminium oxide, is named corundum. When trace components make it appear red it is known as ruby, but all other colorations slide beneath the designation sapphire. Corundum has a trigonal Bravais lattice with an area group of R-3c (amount 167 during the Worldwide https://diamondslurry98653.idblogz.com/35338198/a-secret-weapon-for-diamond