Marc by Marc Jacobs Script Ring
When Marc by Marc Jacobs uses letter sizing like M/L (Medium/Large) for rings, it typically bridges a standard range rather than a single numerical size:
US / Canada Size: Usually spans 7 to 8 (sometimes a 6.5 to 7.5 depending on the specific vintage batch).
Europe (Circumference in mm): Roughly 54.5 to 57 (or standard European sizing of 55–57).