While we associated onyx with black, it is actually available in a range of colors: blue, black, , , ?.
Most black onyx is either black agate or black chalcedony. Natural black onyx is quite rare.
Throughout history the vast majority of black onyx has been dyed. Onyx is a comforting stone for those dealing with grief. It can be used to strengthen self control and for stimulating the power of good decision making. It boosts self confidence, helps ease the fear associated with phobias and balances yin and yang energies.