Beautiful Natural Stone Blue Agate Heart Pendant. This Pendant is 20 mm and hangs on an 18" durable leather chain which has an extension chain to be able to make the necklace longer. This heart pendant boasts the beauty of the Blue Agate stone...Has shades of blues and black...Very eye catching, showing us how nature shows its beauty! Due to this being made of natural stone, the patterns may vary. (See Pictures) All stones are similar but No two stones are the same.