Open a browser window, visit the Rolex site and bring up the pages for the YM Look at the pics on the dealers site and start comparing details, looking for obvious differences Check the hands - thickness, length, positioning of circle and size on the second hand Look at the crown (The bit you wind) does it look too angular, is it too wide, how close does it appear to the original Look at the font of the text, its size and spacing on the face. Does the logo look accurate Look at the bottom at the 'Swiss Made' is it in the right position, is it spaced correctly, does it have minute markers at either side that extend up Look at the date window - Do the numbers appear to be the correct size
There are lots of other things to check for but depends on how much accuracy you're looking for. By what you've said, I think if you match the above criteria to the TTime one you'll be happy with it.