Resurrecting an old thread here...I just unearthed some of my mom's white coupe Centura from the basement. I grew up with it for everyday. On the flat pieces, there appears to be a yellow discoloration on the bottom. If I didn't know better, it looks a bit like the coating on the Corning browning dish (I can't swear whether or not these pieces had been used in the microwave---by the time my mom got a microwave she had a set of Corelle in the cupboard for that purpose). We're entertaining today so I'm not going to investigate too much, but wondered if anyone knew anything.