If Gene's theory is correct, and I have no reason to doubt him, then someone else besides Mr. Whalen has made/repaired/invented brass core chips.

If the date of ten years is correct, wouldn't it be interesting to find out who? AND which chips!

Testing with something that ruins the real chips doesn't seem quite logical. Maybe a dab of MEK or acetone to see if it softens the chip.

Since I don't have any fakes and very few brass cores, I would suggest that specific gravity might work, displacement. Or maybe simple weight with a triple beam scale since the hole filled with plastic will weight less than a real chip?

Is there going to be an X-ray machine at the convention, so people can check chips, or do we have to carry them through security and watch the machine at the airport?

Just some ideas.