This retro French babe is tres chic, and I adore her. 
It is everything I would want in a ring, heavy, solid 18ct gold, with French eagles head mark, and a chunky old mine cut diamond. 
The lovely little groove adds just that extra little touch of sophistication. 
French eagle's head mark for 18ct gold (marked on the outside which is common in these pieces)
Weight approx 11.2g 
Diamond approx 0.65ct (calculated in setting)
Width at front approx 11mm
Width at back approx 4mm 
Finger size K, but feels more like J due to width (fits like approx US size 4.75-5)  Not recommended for sizing. 
Excellent vintage condition