I use a sharp pointed piece of metal - anything that will make a scratch - and on the front ring make one scratched line on the left inside "flat" where the two halves meet, two scratches on the rear. That way I know the orientation of the ring, front to rear, top and bottom.

AKA The P-Man smile

If you cherish your memories with kids, be a good role model . . . . so the RIGHT memories of you mean something to them.