Bella Swan's New Moon Birthday Dress

EW has an article about the dress Bella wears in New Moon birtday scene which fans have been asking about.

New Moon costume designer Tish Monaghan custom-made Bella’s one-of-a-kind dress:

''It was supposed to be a gift from Alice, so I wanted something pretty that Alice would buy, but also something vintage [looking] that would be appropriate for Bella. We dressed it down with sneakers to keep the Bella flavor.''

Source