How much would a platinum playing card cost?

How would one even find this info out?

I got the dimensions of a playing card off Google, but dunno how to figure out how much a platinum card at these dimensions would be weigh?

"Typicalplaying card dimensions- Standardplaying carddecks are 2.5 inches by 3.5 inches (64mm X 89mm) and 0.17mm and 0.24mm thick. Bridgesize playing cardscome in at 2.25 inches by 3.5 inches (57mm X 89mm). Mostcardshave a weight of 280gsm (grams per square meter"