Expertizing Requirements For Single Imperfs

What are the minimum measurements required for expertizing a single imperf (e.g. Sc #534B)?

This is assuming that the single did not come from a known multiple with a cert, of course.

Basically, I want to know when it is a waste of time to send in an imperf for expertizing. Thanks.

534B exists with the oblong Shermack perfs, so any example must at least have wide enough vertical margins to preclude the possibility of trimming.

I'll take a shot at a generic answer to the generic question: The minimum required dimensions would have to exceed the dimensions of an item that could be used to fake it. So for instance, on a 534B, the width would have to exceed the horizontal distance between Schermack type III perfs, and overall dimensions would need to be large enough that it couldn't be a trimmed jumbo 528B. There are some large 528B's out there, so this may be the true limiting factor. Here's a pretty big 528B:

http://www.siegelauctions.com/2007/932/269.jpg

Something like the "534B" below would have "zero" chance of getting a genuine cert (pity the poor person who paid $562 for it):
http://www.ebay.com/itm/371416770106

For other imperfs, you'd need to consider what potential stock could be used to fake it, then determine what dimensions make sense for judging it to be real. Some imperfs (e.g. Scott 1-2) exist only imperforate, so no matter how close they're trimmed, they will be genuine (assuming they're not altered proofs, etc.)

If you have an imperf you're considering sending in for expertizing, post a scan here. Several people could quickly tell you whether it's a waste of time or not.

it was talked about some in this post https://goscf.com/t/45860&SearchTerms=315

Thanks again! I got a lot of the offset W-F imperfs (#531-535) last week. I purchased it for the #533, which looks genuine. It includes a Type VII (534B) which is almost definitely a trimmed 528B (I'm about 99% sure). I never was going to try to expertize it, but it was the stamp that triggered my question.

I knew W-F coils have ideal measurements (25mm x 21.5mm even though many true ones are slightly less) but I didn't know if the same measurements applied to imperfs, specifically the 534B. I guess the distance between stamps on the original panes would be part of the answer.

I wonder if one could create 3D printed templates or gauges for this purpose. They would not have perfect long-term temperature stability, but that could be addressed by printing a 1-2 cm calibration line on the gauge, which could later be checked against another reference instrument. 3D printing should have the precise tolerance needed for a successful tool. The same could be done to create a gauge for measuring rotary versus flat plate, a substitute for the old stamp-with-cut-corners trick.