Antique platinum filigree diamond dome ring

Antique platinum ring with 1ct total weight in diamonds.  The 3 large diamonds weigh .20cts, .35cts and .20cts.  All the diamonds are old cuts, VS2-SI1 in clarity, G-H in color.  The ring measures just under 1/2" wide, it's a size 6 and can be sized.  Circa 1920.