Crescent Moon Black Obsidian Pendant 1" (Chain Not Included) This beautiful crescent moon shaped pendant is made with a natural black obsidian gemstone that is approximately 1" in diameter. The gemstone is a deep black color with a glassy finish. The pendant hangs from a sterling silver bail. Black obsidian is a type of volcanic glass that is known for its protective properties. It is said to absorb negative energy and promote clarity of mind. It is also said to be a stone of strength and grounding.