Leon I'm just thinking out loud here, but would a gram scale be able to pick up a counterfeit or skinned T206? perhaps even a black light or digital microscope? What are the telltale signs to look for? Thanks

A good magnifier and knowing what to look at as far as the printing and edge quality goes will detect most of them.

Blacklight will pick up a lot of them too.

After that it gets a bit tricky.

I don't have the number handy, but at one point I measured the thickness of several T206s and they were all the same. Within reason, I didn't look beyond thousandths of an inch, and given the tech of the day I'd say +/- .001 is reasonable. If I remember it correctly there was no difference in any of the ones I measured.

Just seeing a lot of originals up close is probably the biggest thing. After a certain point, the ones that are "wrong" will be more obvious.
That's also something I don't have much advice on. Most collectors who started a long time ago have probably held more T206s and other prewar cards than most newer dealers have seen. One show I went to there were probably 5-6 dealers who had between 50 and 100 in stacks. Not even a plastic holder. That just doesn't happen today.

The problem with these cards is that there is extra paper and glue on there, which would totally throw off the weight.

I have heard of people using scales, personally I have not and can't imagine that changing.

All you need is a good dial caliper that you can read thousandths of an inch on. Like Steve said in a previous post .001 is a lot of difference in a baseball card. If a card has been skinned you will know for sure.

Not recommending the seller buy Lyman is a good quality caliper.:) https://www.midwayusa.com/product/10...tainless-steel

I have one similar to this one. I like the instant inch/metric conversion.
While I wouldn't rely on it for any really critical machining, mine has been very reliable and accurate.
The digital readout may be easier for people not used to the dial caliper.

I also don't have any particular recommendation for the seller, I just picked one in the price range of what I paid for mine that looked nearly the same. Other similar ones are available a lot of places for a bit under $20 to a bit over $40. One with a good brand name that would look better if you're doing serious machining will run around 2-300 But for most of us that's not necessary.

https://www.cabelas.com/product/Cabe...E&gclsrc=aw.ds

And for what it's worth, I made a halfhearted attempt at finding a nearly matching cardstock without going to a wholesale paper supplier.

Craft stores - Nope.
Hobby shops - Comic backing boards are close, and don't react to UV, but they're too thick.
Other retail sources- Nothing close at all.

Really? How many have you handled?