18-karat white gold. Tourmaline gemstones = 3.30 ct. Tw. Available in size 7.5 only. Put (the right) Ring on It: Size Guide. Ring can be re-sized by any professional jeweler; however if re-sized it will not be accepted for return. It is customary to treat most gemstones to achieve enhanced colour and durability. Some of these treatments may not be permanent and may require special care. Accompanied with manufacturer's packaging. Our products are 100% genuine.