Ring size: O, but I can resize it if required. Just get in touch by clicking the 'ask seller a question' button prior to purchase.
If you´re not sure what finger size you need then the following link will help: http://www.notonthehighstreet.com/email/2013/partner_material/Ring-Size-Guide.pdf
The ring shank measures 3mm wide and 1.8mm thick. The round faceted moonstone measures 3.5mm in diameter and the gold concave dome has a diameter of 10.5mm.