~~~ as to how the club learned of these UV markings on chips.

Years ago I was trading with a German National dice collector living in Berlin, I think.

I would send him rare Vegas dice in balance for rare German casino chips... and one day while we were exchanging letters he explained to me that while he was inspecting some dice with his blacklight, he passed the light over some chips and noticed the markings. I was amazed, as were other long-time collectors when I told them of his discovery and I suggested he write an article for our club magazine; which he did, and we all learned of these markings at that time.