They do not correspond to any "model year" for any particular reference watch.
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Bain says that just last year, a group of counterfeit ceramic Rolex Submariners snuck into the market.
“If you didn’t look at one next to the real one, and you just looked at it alone, you probably couldn’t tell it was fake,” he says.
Up until recently the exchange cases started with 44xxxxx.
It is believed that those numbers have been used and later re-case numbers begin with 47xxxxx.