diamond and platinum ring

A platinum solitair ring set with an old brilliant cut diamond (app. 0.75 carats, F-G, SI1, one small white inclusion in the bottom of the stone), signed and numbered: J.E. Caldwell & Co., N2470, V.S., circa 1925.

weight: 3.3. grams
ring size: 17.75 mm. 7.5 us