This is a really wonderful Ben Zuckerman coat, in cornflower blue silk trapunto. Trapunto, from the Italian for "to quilt," is a method of quilting that is also called "stuffed technique." A puffy, decorative feature, trapunto utilizes at least two layers, the underside of which is slit and padded, producing a raised surface on the quilt.
This coat is empire waisted with a Watteau or sack back, which would likely date this coat to the mid 1950's.
Photos courtesy of Vintage LoveLove 88