The only reason I do not call this Ring antique is because the 18 karat gold hallmark was added at a different time from the manufacture of the Ring and there are no original marks at all,

 The Ring is 18 karat Yellow and Whit Gold and has been acid tested. 

The composition , craftsmanship and cut of the Diamonds all scream early 20th century. a stylized 18 karat yellow gold shank is connected by shoulders to the top of the ring which is 5 prong settings that have been seemingly fused together all handmade,

 The central stone is 3 mm Round and the four surrounding stones are 2 mm Round , total Diamond weight approximately 0.35 points The stones are all old cut and of a nice quality.

 Size of Ring - 8.75 US ( 17 European )