Onyx is a protective stone that enhances strength, confidence, stamina and concentration. It aids anxiety / stress and dispels feelings of depression.
Its energy is thought to help alleviate feelings of grief and confusion. When we're feeling listless or lost, it's recommended we hold on to Onyx to help enhance decisiveness and focus.
It's a stone of strength and self control. As humans, we can always let our emotions get the better of us but with the right guidance and the right energy we don't have to. Onyx helps us think more clearly and rationally.