I did find the mark in a book, it says this mark was used from 1940 to present. It is possible it was aquired at a movie theater. It started in the 1920's when the method of making glass got really cheap. Depression Glass started this way. It was offered at movie theaters, in Soap Boxes and many different ways. This was a popular thing into the 60's, I remember mom in the 60's getting free plates and etc, for buying x amount at sears. This was of course to get you to come back. It was said if you went to the same movie house enough times you could collect a whole of set Dishes.
I also check out replacements as suggested by KC, I did not see your pattern called "Century" Listed. But with the name, and pattern name, with a bit of surfing around you will find the date and value of your items. They are wonderful looking and would be in my Fancy catagory, espically the Blue and Gold of your set. I think these could prove to have a good moderate value to them. Thanks for sharing they are wonderful.