Size chart
The best option to find out your ring size would be to visit your local jewelry store and ask them for help.
Othervise take a ring you already have and measure it straight across the ring (in the exact middle) of the inside edges of the ring, to get the diameter Ø (mm).
Try to be as exact as possible. Choose the ring size closest to your size.
Rings made in a specific size are non refundable.