Green Stuff World Mixed Green Glow Translucent Crystals - Medium Decorate bases, dioramas, and terrain pieces with these amazing resin crystals. Make them look unique, personalized, and stand out. This set includes medium crystals of various shapes and sizes. The crystals can be single or multiple, with some pieces carrying up to 3-4 crystals. The approximate sizes of the pieces are from 9mm to 16mm tall. To activate glowing properties, the crystals must absorb ultraviolet light beforehand, either from natural light or from ultraviolet torches (UV Flashlight) Contains 50 crystals.