[ls7plus]

I can tell you that the grading companies look at the edges of the cards to determine trimming, at least with Topps and other cards from the same era. The sheets of cards were originally cut using a "guillotine" shear method, leaving relatively rough edges on original, non-tampered with cards. Back in the early '90's, before and just as the grading cards were coming into being, they were certain unethical dealers who specialized in running off-grade cards through a paper press, making them slightly larger, and then trimming them back down to size, losing their worn corners in the process. These shannigans would leave the cards with corners appearing sharp and unworn, in apparent NMt-Mt or better condition to the naked eye, and greatly increase their apparent value. Viewing them under a loop, however, revealed very sharp, clean edges quite different from those an original, untampered with card would possess. Sometimes the scammers would only run the upper and lower portions of the cards through the press, thus enlarging only the borders, but leaving a distinct "pinched" appearance at the corners as a tell-tale sign that the card had been trimmed. During that time period, many dealers, as well as myself, aware that this unsavory process was not an infrequent occurrance, would only purchase raw cards in apparent high-grade after viewing their edges with a loop. The grading companies do the same. Card sizes were not absolutely uniform, but had slight variances. You cannot determine if a card has been trimmed by measuring it; only by looking at the edges under magnification. Thus, if a card has been graded, it most likely has not been trimmed.

Hope this helps,

Larry