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 - more in their own sections below.
FLAME AURA: is treated with titanium and niobium, resulting in the crystals having a rainbow coloured appearance, with shades of gold, magenta, green and aqua-blue being prominent. This is quite a forceful stone with a vibrancy and power that is very "awakening" and energising. Titanium is a great connector, and as such this crystal has great uses in journeying and connecting with Higher Guidance through meditation. It also carries the Rainbow Rays, which can help balance and charge each energy centre and indeed the auric field - try laying in a "Star of David" grid of 6 of these crystals, preferably double-terminated, otherwise points-in.