Onyx

While onyx is generally thought of as a black stone, it can be found in grey, white, blue, brown, yellow and red.

This is a stone that gives strength and support to the user or wearer. 

It provides support in difficult or confusing circumstances and during times of stress.
Black onyx is used for meditation, grounding and centering. It gives strength while acting as a memory shield.

As onyx holds physical memories it can be useful in past life work and can heal old grief and sorrows.

And, should be worn on the left side of the body either as a necklace or perhaps as a stone kept in one's pocket.