If you’re checking a Rolex before selling or borrowing against it, look for the...
https://super-wiki.win/index.php/Is_It_Smart_to_Sell_a_Rolex_If_You_Think_It_Might_Keep_Appreciating%3F
If you’re checking a Rolex before selling or borrowing against it, look for the reference number engraved between the lugs at 12 o’clock. On many models, you’ll need to remove the bracelet to see it, so don’t force anything—ask a watchmaker to help