We have a Mother of Pearl oval buckle vintage item.  It measures about 1 3/8" in H x about 1" across the center x about 1/16" in D.  The center length of the opening on the flat is about 7/8".  The front is in nice condition.  The back has a bit of discoloration on the center bar in the middle - I tried to show this in my photo's.

Mother of Pearl Oval Buckle Vintage