It is an essential device in identifying colored stones. While it was originally intended to rapidly differentiate between genuine Emeralds and the pastes and doublets which resemble them it also is a valuable aid in identifying other colored stones as well. Designed to transmit only deep red and yellow-green light and the best results are obtained when stones are examined under a strong electric light. Chelsea is definitely a helpful tool in identifying certain red blue and green stones. With Chelsea filters you can differentiate the genuine emeralds from the fake once as well as checking the authenticity of aquamarine and sapphires with comfort and ease. Made of metal, Set includes: 1 x Chelsea Filter 1 x Leather Carry Case Standard Packaging Box"