Here's a sleek prom dress in blueberry blue satin. Affordably priced under $100, this long formal dress is ideal for prom and black-tie galas. The form-fitting evening dress has a sleeveless bodice with a plunging v-neckline. The neckline is supported by a sheer-mesh inset, while spaghetti straps form a caged detail against the open back. This long blue prom dress has a curve-cradling skirt that skims past the hips and, with a slight flare, ends in a dramatic train. Beyond chic, this open-back blue prom dress, from Rated PG by PromGirl, offers stand-out style.