Hello, black onyx is a variety of quartz found in India, Arabia, and South America. Its glassy luster, rich hue and hardness up to 7 on the Mohs scale made it a popular material for making jewelry as far back as the 5th millennium BC. The ancient Egyptians, Babylonians and Aztecs considered black crystals to be sacred, able to protect against negative energy directed at the one who wears anything inlaid with them. Currently, mens gold black onyx ring is one of the best jewelry options for men, according to modern lithotherapists.