This lovely Guess dress in a Size S (Small), can be worn with or without straps.  Gwyn (pictured) is about a size 8, so I think this would fit around a Size 10

 - but please be guided by the actual measurements.  The lining has some stretch to it.

Materials:  100% polyester

For your convenience, we provide these measurements as a general fit guide only (measured in unstretched state).  You should compare these measurements to a similar item that you currently own.