Black Star Aquamarine

Black star aquamarine is a trade name for natural beryl that looks dark brown to black because of dense, oriented inclusions, mainly of the iron-titanium oxide ilmenite, in an otherwise very light blue or pale green aquamarine host. The oriented inclusions give a sheen (schiller) and, in cabochons or beads, can show a six-rayed or even twelve-rayed star. Gemologists usually call it black beryl or star beryl; the dark appearance is linked to the inclusions and the brown colour zones around them, not to the pale aquamarine body colour.