This is hard to explain in writing, but you must look at the edges of the card while holding the card flat to your eyes. The card should look like this when you are examining it:
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If you are only looking at it from the face/front or back, you are missing many of the tell-tale signs.
You cannot just measure a T206, for example. You have to look at the flat sides/edges. If you ever have the chance to compare a trimmed edge to a not trimmed edge the differences do jump right out at you.
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