Glass beads are composed of sand (silica), soda ash (sodium carbonate), and limestone (calcium carbonate), and crystals are traditionally made with the same ingredient with the addition of lead. Adding lead makes crystals turn crystal clear, allowing light to reflect inside the beads making them sparkle. It is also known lead also makes crystals heavier than glass beads.
*Information sourced on like @ HTTPS://FACETJEWELRY.COM/STRINGING/RESOURCES/2018/03/ALL-ABOUT-CRYSTALS
