Rose gold plated copper spiral ring in the ancient Greek style. 
I use US ring sizes. To find your size, use the pictures I’ve included of the US ring size scale. You can measure the diameter of an existing ring or you can measure the circumference of your finger with a tape measure. If you don’t have either, wrap a strip of paper around your finger, mark it with a pen and measure it afterwards with a ruler. 🙂
The design of the ring means that it can be adjusted a little either way.