I think that perhaps in this particular instance the certain something may relate to the fact that the Original 52 model came into being shortly before Original regained their Diana brand name. Though it may seem simply a name change- to a collector that makes the early model more desirable since there will be way more Diana branded model 52s around than Original model 52s.
But I also suspect that Diana much like other makes were producing guns back in those days that had that little more of the human touch in their build. I admire the lustrous bluing on my Jubilee 45s and whilst the current Diana bluing is good it doesn't seem quite as good as of old.
Maybe there is more pressure to produce the quantity of units these days and it was more about quality back in the 70s-80s?
Or maybe I've got my rose tinted specs on this morning
Dave