SGC cert numbers are formatted xxxxxxx-xxx, seven numbers indicating the submission and three numbers representing each card in the submission.
So, cert number 1285643-010 would indicate that the card was tenth card in the submission. All cards in the submission would have the same first seven numbers.
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The submission numbers are generated by using the online submission form, or the submission packets include paper forms that are numbered. Or SGC may assign a submission number in some cases.
It is not an exact science because an older form may be used by a submitter who sends the cards in for grading well after the submission number has been generated.
In general though, submission numbers lower than 130xxxx or 820xxxx were used prior to mid-2012. You can also assume that the holders with the hologram on back predate mid-2012.
Another way that I date when cards were graded is that SGC flips have been notoriousy bad the last few years being miscut and not enough ink used or the cert number printed in the green border.
Someone else may have other ideas. I do not know if SGC would look up the cert numbers for you, but you might check with them. The key point is that you will have greater results if you have cards reviewed that were originally graded before mid-2012, and those in the mid grades where half grades did not exist at the time.
