The stone is malachite and azurite growing together. The key is the key cup from the lower ring key mechanism on a prototype clarinet I bought several years ago. The maker didn't end up sticking with that design, so I decided to use it to make jewelry.
The chain is 18" long sterling silver.
Fun fact: in about 400 years, this stone will be completely green, because the azurite will have oxidized and turned into malachite!