This is a lovely piece of dark green sea glass. It is so dark it looks black- hence the name "pirate glass." It was most likely part of a wine bottle long ago. The bottles were a dark green to keep light/sunlight from affecting the properties of its contents. Now it is a one-of-a-kind pendant, secured to a silver-plated chain by a sterling silver pinch bail. Choose your chain size: 18", 20", or 24" and indicate at time of purchase.