It is possible to treat natural clear quartz (and occasionally other suitable minerals, such as danburite) in a process that bonds atoms of precious metals to the exterior / matrix of the crystal. These enhanced crystals have a coloured appearance, depending on the metals used in the process, and carry an added energy that, unlike "dyed" crystals, add to and extend the usual attributes of the base material. These crystals, as well as a few man-made minerals such as Gaia stone and Pink Lazurine, are very usable in crystal healing and meditation etc - their uses vary widely according to their nature -
OPAL AURA (also known as Angel Aura or Rainbow Aura): is treated with platinum, silver and other trace minerals, resulting in the crystals having a pearlescent white colour with an iridescent finish. This crystal has a sweet, fine and high resonance, which seems to sing in the hand. It carries the Rays of the Divine Feminine and of Cosmic Enlightenment, and is a very "connecting" stone. If you wish to extend or activate your upper chakras, whilst retaining a sense of peace and serenity, then this is an excellent crystal to work with. It also brings in the full spectrum of Light, which can help purify and cleanse any of the energy bodies or centres whilst strengthening purpose and resolve.