Rhinestone Settings Prong ss12 (3mm) Hand or Tool Set Silvertone Pk/100 Tiffany Prong Settings: Prongs push through fabric from back. Set stone in between prongs and close prongs over stone using a hand setting tool, the eraser end of a pencil, or a blunt tool. Prongs will show over stone. Prong (leg) length is approximately 1/8".