These hoops are marked 925 on both the pin and the main body of the hoops, indicating that they are fully silver. The stones are sparkly cubic zirconia (CZ). In the years that I have owned them they have not tarnished, so I presume they are plated with rhodium, platinum, or some other stable metal. Outer diameter approximately 31mm, inner diameter approximately 21mm. Width of stones is approximately 3.8mm (nearly 4mm, but not quite). The springy omega backs on these hoops make them quite secure and easy to put on. I’ve received many compliments on them over the years, but I am culling my redundant jewelry. Please help them find a new home!