its different types of precious metals in small amounts throughout the glass
like dude said they use gold and silver
i think they also use copper n others too
MizeryU Reviewed by MizeryU on . not sure if i killed my color hey i just let my color changing glass piece sit in rubbing alcohol and salt for a little less than a day maybe like 18 hours, but now that i rinsed it and everything all the color from my piece is gone, now its just all clear.....will the colors ever come back or did i ruin it?? :confused: Rating: 5