Herkimer diamonds are doubly-terminated natural quartz crystals found in Herkimer, NY. I used a transparent CD blank to cast a spectrum on this one for Burst of Color, but later decided it didn't meet the challenge. Oh well, it still looks cool.
I think it's quite fitting for the challenge and would have been one of the better scoring entries. Of course, I should have told you that last week...shouldn't I have?