Sapphire Swarovski 2038 Hot Fix Xilion Flatback Rhinestones are available below. These Hot Fix Rhinestone are amongst the most brilliant found anywhere in the world. It can easily be applied to fabrics using the heat activated glue already applied to the back of the stone. The Xilion Hot Fix Rhinestone is available in Sapphire in the sizes listed below. These stones are made of "advanced crystal" and are lead free.