The Corning Museum of Glass has a number of Coin glass pieces in their 19th Century pressed glass display. Most of the pieces I saw were not exact copies of coins, only similar in appearance. I don't recall seeing any medallion pieces, only images pressed into a plate or serving piece. My experience from years ago was that the curator was very helpful (at one time, I was interested in cut glass). Maybe that's still true today. Hope this helps
I can answer some of your questions about the glass Columbian half. How do I post photos from my computer?