Sterling Silver & Black Onyx Secret Garden Ring. -925 sterling silver. -Black Onyx: 6x4mm. -High polish, oxidised. Black Onyx is a good stone to have around during times of mental or physical stress or bereavement, as it provides strength and support during difficult circumstances. Black Onyx is a soothing stone said to help alleviate fears and worries and to help you to feel comfortable within yourself and in your surroundings. It is also believed to promote stamina and vigour and to encourage the making of wise decisions. Black Onyx is said to promote self-control helping the wearer to keep excessive emotions and passions under control.