J. Crew Squareneck smocked featherweight satin cropped top. Size small. Black.

From the J. Crew website: "Smocking is one of our favorite design details right now. It makes cropped styles like this one so sweet (not to mention comfy and stretchy too). Plus the lightweight, silky fabric looks good and feels good because it's crafted from recycled materials, like plastic bottles, fabric scraps and old clothes. Body length: 21 1/4". Poly. Machine wash.