I'm looking at late 1950s to early 1960s Tudor Oysters. I've noticed that a fair number do not have the Rolex stamped case back and have the reference number and serial number on the case back instead of between the Lugs. Is there a reason for this? Are these still considered true authentic/original Tudors? Also a lot seem to have the sticker still in tact, is there also a reason for this?

 

That case-back is ok, but to say if the entire watch is legit, we'd need to see a lot more photos. BTW, someone just put that sticker on the back. It's not original. You can buy them on Amazon.