Amarra Long Formal Dress 88371 Cao Bang, Vietnam: What You Need to Know Before You Go. Get ready to make a statement at prom in Amarra's form fitting long dress. The bodice boasts a sweetheart neckline with hot stones for a touch of sparkle, while the sheer sides and off the shoulder straps add a flirty touch. The adjustable lace up open back and high leg front slit in the floor length skirt complete this stunning look.