Octagonal Diamond Ring Circa. 1970 American 18K white gold. Tested with 18K acid. Diamond is approximately .65 carats. F color SI1 Bezel set oval cut in an octagonal setting. Diamond tested with a diamond tester. Hand-set. Marked "750" and with 2 hallmarks inside shank. Size 6 1/4. Can be easily sized by a jeweler. Great modern design. In pristine original condition.