The most reliable way to determine your ring size, is to be measured using sizing rings at a jeweller's shop.
Be sure to be measured using a sizer of approximately the same band width as the ring you would like to wear, as the width can affect the size quite a lot.
Alternatively, you can use a ring sizing belt, please let me know if you need one when ordering your ring.
All Glasswing rings are measured by the standard British (Wheatsheaf) scale, however I can convert the size for you if you only know your own country's system.
The measurements below are for a rough guide.
If you have any difficulties at all with working out your required ring size feel free to contact me and I will be pleased to help.