You need to go to original project and ask there.
I think this is a question for a specific project. You'll get a better response if you post at the bottom of the project rather than the general forum.
here are the directions: https://colormadehappy.com/diy-glass-cracked-gems-stones-jewelry/
By using this method, they sparkle so beautifully, if used outdoors. Also, try adding to a bird bath or water fountain. just drop a few on top,for the sparkle effect, or in planters such as succellents.