The stones in this ring are just stunning. 
A gorgeous rich green cushion cut emerald, flanked by sparkling bright old mine cut diamonds. 
The setting is a buttery rich 18ct, which just sets the whole thing off perfectly. 
Though the stones are likely older cuts, I would place thing ring in the early 20th century, the arts and crafts styling of the shoulders is really pretty. 
Very faintly stamped 18ct - tested as the same. 
Weight approx 3.46g
Width at front approx 14mm
Width at back approx 2.3mm
Diamonds approx 0.25ct in total (calculated in setting)
Finger size N 1/2 (USA approx 7.25)
Very good antique condition