18-karat gold over .925 sterling silver Multicolor Tourmaline gemstones = approximately 17.00 ct. tw. Approximately 17in long Lobster claw clasp closure It is customary to treat most gemstones to achieve enhanced color and durability. Some of these treatments may not be permanent, and may require special care. Please note: In product titles ct. tw. refers to the total carat weight of all diamonds and/or gemstones combined.