Unique vintage princess cut alexandrite engagement ring rose gold under halo moissanite ring for women personalized dainty wedding ring bandThe Alexandrite ring Often described by gem aficionados as emerald by day, ruby by night, alexandrite is the very rare color change variety of the mineral chrysoberyl. That is why the color of Alexandrite changes under different lighting conditions. Main Ring: 7mm princess cut Lab alexandrite. Round 1. 0mm moissanites. Material Metal: 925 sterling silver, Solid 14k 18k gold,platinum PLEASE choose silver or platinum if you are allergic to nickel.