Photo is approximate size (computer setting vary, therefore images may vary also. Use coin [18mm] as a guide.) Inside dimension is 3mm Bezel cups provide an easy way to set your stones and finish with clean lines and professional-looking results. Use with cabochons for everything from earrings to pendants. Metal type: Sterling silver Metal color: White Fabrication Method: Die struck Gauge/thickness: 32 ga. Shape: Round Style: Bezel cup Wall height: 1.9mm Mounting/Bezel size(s) shape(s): 3.0mm Country of origin: United States ROUND 4mm, 5mm, 6mm, 7mm, 8mm, 10mm also available. See my other listings. Sold by the six (6) piece lot. These are so well priced, why waste your time making them. Sterling silver 3mm (inside diameter) machine made plain edged bezel cups are easy to use. Solder them in place and set your cabochon stones with a bezeler.(bezeler not included in this listing but available in my eBay store).A very good addition to your work bench materials.