Ring with 3 diamonds

Ring with 3 brilliant-cut diamonds totalling ca. 0.55 ct, central brilliant-cut diamond ca. 0.25 ct, ca. WHITE-STW (H-J)/VS, 18K white gold, 3.3 g, ring size: 55, W: ca. 1.8 - 4.4 mm, 2nd half of the 20th century, minimal signs of wear.