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[precioustimewatches]

hi,
i'm a watch dealer and started to deal with Rolex. i'm a, dealer for over a year now and this month was the first time i bought an expensive rolex. Yes, i did not have the funds and intrest purchasing second hand watches more then the retail bud god... everybody is looking for a rolex...
So my question is: i bought a GMT master II which has mixed serial. how can i find out from what year it is? (bought it without a card).
Acoording to my firneds / other watchdealers if the buckle is shiney and not math, it is over the year 2015. but still, i would like to know since if i sell it and client will ask, what should i say? i can easily say 2018 and it's not....