I went to a mineralogy show for college, and saw some "rainbow quartz" which is quartz anodized with a titanium oxide coating. It produces a highly reflective array of "interference" colors, think bright purple, gold, blue and dark reflective black.
No dye involved, it's entirely caused by the cystalline rearrangement layer which is so thin that it "constructively" and "destructively" affects different wavelengths passing through it.

Apparently you can anodize titanium and produce very uniform and predictable colors, and they change lighting properties subtly from different angles. Someone should definitely anodize their titanium frame blue
I don't know if you'd have to block off the bb and headset though, apparently the titanium oxide layer grows both into the metal and out of it but it's on the scale of microns.

http://www.webamuse.co.jp/new/produc...ilent_gold.jpg