Sleek and modern, this two-piece long prom dress offers a sophisticated look for your formal celebration. The designer evening dress from Harper and Lemon features a high-neck crop top with cut-in shoulders. A bold collar circles the neckline before attaching over a beautifully framed triangle-shaped back cut-out detail. The lovely formal dress has a slinky floor-length skirt that smoothly hugs the curves before flowing down to the floor. Ideal for a winter formal or gala, this two-piece long prom dress, under $200, is affordably priced and on-point for prom 2018.