THE BLACK RAY IN CRYSTALS
When the black ray manifests in crystal form it combines the properties of the crystal with the energy of this deep, mystical colour.
Black holds all the colours of the rainbow within it. It represents the Earth and stability. Black stones are symbolic of self-control, of resilience and quiet power. They are sometimes viewed as protective, but black stones are most often used to ‘earth’ a person. Mystically, black is the colour of the outer spaces, of the absence of light.
WHITE AND BLACK
White and Black symbolize creative activity. White symbolizes the presence of colour, while black symbolizes its absence. There is a wonderful mystery in white and black which touches upon the deepest secrets of the universe. Ancient alchemists communicated many teachings about the contrasting forces of white and black, and the results that could be obtained by their fusion. Perfect balance of these two colours (or symbols) is known as polarity. Truth, too is a polarity. When we reach this state of balance, a new earth will be created. When white and black merge, human evolution will reach its goal -- divinity.
THE SILVER RAY IN CRYSTALS
When the silver ray manifests in crystal form it combines the properties of the crystal with the energy of this creative colour.
Silver and some grays can be used to amplify the effects of other colours, much in the manner of white. Silver is effective in meditations and It can help us discover and apply our creative imagination. It activates innate intuition. Silver helps to quell erratic emotions. It is a natural tranquillizer. It calms the hormones and allows the physical and mental functions to flow freely. It helps reflect distortions so that corrections can be made. It teaches us that mistakes are not necessarily negative - the great teachings come from our mishaps. It can help absorb negativity.
Reference: Healing with Color: An experience of Aura-Soma, Philippa Merivale; New Cosmic Crystals, R.A. Bonewitz