What was the importance of Daisy’s golden pencil which she handed to Tom?

Daisy's gold pencil is a status symbol.... it speaks to Daisy's class consciousness.

"Go ahead," answered Daisy genially, "And if you want to take down any addresses here's my little gold pencil. . . ." She looked around after a moment and told me the girl was "common but pretty," and I knew that except for the half hour she'd been alone with Gatsby she wasn't having a good time.