This is inspired by the Swarovsky Signity watches, and this timepiece by designer Ilya Yakovlev has a surface made from real crystals that are backlit by LEDs.
One interesting feature is that you can increase the luminosity and change the colors to suit your mood. As far as I can tell, it’s a concept that we probably won’t see for a long time yet, but it is interesting. I think it probably would need more functions aside from just being a watch. They should look great in the dark.