Those are a little better.. And it looks much better. everything looks fine about it..
For me I'd say its 99.9%,,,reason not 100%.. IF you were sure about the seam.. You see if there really is no seam its cast which would mean postwar.. Sometimes they match a solder and flux good to the ring and a experienced jeweler can solder it up and finish polish so good its almost impossible to see. Hopefully thats the case as this ring looks good...