One-size-fits-all. Each ring is a one-of-a-kind creation, made on the Venetian island of Murano, Italy, using Murano glass with encased Gold Leaf. The band is gold-plated and adjustable to fit practically any finger size. They also make a great "scarf ring". Just feed your scarf through the ring, and you will have a decorative glass focal, to keep your scarf in place.
The glass face of the ring measures 25 mm across (just over 3/4 inch).