Black Tourmaline is known for its protective and grounding properties. If you are finding it difficult to stay present and negative energies are persistant, then this stone will be useful to have around.
 
Amethyst is a great reliever of stress and depression, and balances the mood. It is a good companion in the process of healing from pains of all kinds. Combined with Black Tourmaline this necklace is a powerhouse of calm and grounding energies.