You might try the “softsoap” type cleaner they make for smooth top ranges. I had one with a Corning top-like the Corelle plates-and it removes stains without harming the design. It’s not very expensive and it lasts a really long time. Use just a small amount and your plates will look new. I use it on all my corning ware as well as the dishes. One bottle last me over a year and it costs around $5.00 in my area. 8) ;)