The crescent-shaped wooden pieces that are most often pendants in our jewelry come from the seed capsule of the Sandbox Tree (Hura crepi- tans). The piece is natural, just sanded a bit around the edges and drilled for stringing.
The seed capsules grow together in a small pumpkin-shaped "grenade" that blasts apart in the heat of the day, scattering the individual capsules and seeds over the ground. It is very startling to be walking by a tree when one happens to explode, it sounds a bit like rapid gunfire. And every time I manage to procure a complete one of these "gourds," it catches me by surprise as it eventually explodes in the house. Once I even blamed the kids for mashing one up when I found it all in pieces, until I realized what was happening. European Colonists would glue it together before maturity, retaining its round shape, and use it to hold sand as a blotter before paper blotters and ball-point pens -- leading to its name: Sandbox.
The bark of the tree is covered with sharp spikes, giving it the 2nd name of "monkey no climb." Enjoy your piece of the Caribbean!