0.53 ct Antique Vintage Platinum Round Transition Cut Diamond Engagement Ring

An antique vintage platinum three-stone round transitional cut diamond engagement ring, 0.53 ct total weight. The center is a natural transitional cut diamond of approximately 0.33 ct, H-I in color and VS2-SI1 in clarity. Two round Old European cut side diamonds add approximately 0.2 ct, H-I in color and VS-SI in clarity. The ring is stamped "10%RID.PLAT" but tested at approximately 88% platinum; metallurgy standards were less precise in the early 1900s. The ring weighs 5 grams and is a size 7.5.