925 Sterling Silver (stamped) and Natural Black Onyx Stone Necklace is 16 inches with 2 inches extender, can be adjusted to 18 inches Pendant is approximately 32mm high x 10mm wide x 10mm long Elegant, simply and beautiful!! The natural stone charm may slightly vary from the picture. There can be small defects or variance of color and patten on the stone due to the use of natural material.