I missed the shows but it sounds like some Craft Style double sided shimmer card I bought a couple of years ago from C&C. Mine is thinner than Centura Pearl more around 200gsm and a light ivory colour. It cuts well on my Cameo and is good for boxes.
I too like Centura Pearl from Crafters Companion and use it for most of my cards. I have seen it in the art section of either Hobbycraft or The Range, but in A2 size. Very big sheets so never bought any.