Level Up Dice - Crown Crystal Purple Script HPWelcome to the next level in material, we would like to introduce to you our Optically Clear Crown Crystal. After much searching to find the right medium for our glass range, as well as many hours of testing, we are proud to present the worlds first optically clear crystal set of dice. The same material used in many lasers and optics, it sports an index of refraction of 1. 5, this is a clearer medium than glass or Zircon and also sports a higher