International silver

So, I am helping my 96 year old dad clean out his house. He has boxes and boxes of IS from Casey hotel in Scranton, Pa. Most are things like serving utensils, ice buckets, silver tea sets. But, this piece is so amazing. I think it is unique. Very heavy, approx 12x9 has 8 glass inserts (no chips).
Anything you can offer regarding what it is called, maybe about when made, value. Etc. Thanks