Silk and silk thread

[astrea.livejournal.com]

A question for all of you seasoned seamstresses: Do I need to use silk thread for sewing with silk? I bought this silk bag yesterday that I want to reconstruct into a camisole, but all I have is polyester thread and I remember seeing silk thread at fabric stores before. I'm mostly just going to be doing a couple of hems, I think, so would it be a complete disaster if I used polyester thread?
Thanks for your help!