A woman's sack of blue silk figured in a diamond pattern, with brocaded floral sprigs in pink and green. The sack is open at the front, with half-stomachers on the bodice fronts and elbow-length sleeves with double, scalloped sleeve ruffles. The bodice, sleeves and stomacher fronts are lined with linen and stitched together. There is a wide vertical pleat in the bodice. At the back are two double box pleats stitched at the neck line. The sack is made of 1 width of silk with a partial panel and a pieced panel on each side of the fronts. A waist seam runs from the front opening to the bodice side seams. The skirts are sewn to the bodice without pleating, with pockets in the side seams. A narrow band of gathered ruching runs around the back of the neck, down the bodice fronts and continues down the front edge of the skirts. A narrower ruching edges the sleeve ruffles.

The sack was altered at some point, probably in the 1770s, possibly for another wearer. The pleats at the back were reconfigured. Fold marks and piecing on the sleeves suggest remaking. The lining of the bodice may date from this reworking.

The sack was altered for fancy dress in the late 19th century. The train at the back was sewn up, the right sleeve let out and hooks and thread bars added to the stomacher fronts.