Black? Yes, but this two piece vintage 1920s dress ensemble is anything but basic! There are two pieces - inner and outer dresses - that were intended to be worn together, but a modern woman might wear the pieces separately as well. The pieces are tied together visually by the abstract embroidery in pink, blue, yellow, and dark gold metallic used on both. 
The inner dress is intended as a slip, straight cut with narrow straps. The bodice is adorned with a deep "U' of embroidered fabric. A former owner altered it to add more shape with long vertical darts in back, and took it in at the side seams, narrowing the waist and hips by about 1" on each side. I have shown it in one photo pinned to Josephine. The 8" of different fabric at the hem also looks like an addition. 
The outer dress has a deep wrap front bodice with an ascot-type collar with 15" long ties that can be worn in more than one way. Full sleeves gather in at narrow cuffs. A peplum softens the waist over the long straight skirt that ends with a 10" tier of inverted pleats that add softness. There is extensive embroidery on the outer dress - entire back of the bodice and most of the front, the peplum, and the upper half of each sleeve.

SIZE: No label. Removing old alterations to inner slip dress could add up to 2" at the waist and hips - see Condition report for details.

FABRIC/COLORS: Primary fabric is crisp sheer black georgette, fiber burn test suggests silk. The fabric of the inner dress is more opaque and crepey, except for the bottom 8" - that feels silkier and more like a newer lining fabric, even though fiber burn test says silk. 

TAGS: No tags.

CLOSURES: N/A, each piece slips on over the head. The sleeves of the outer dress close with small snaps.

CONDITION: Overall condition is very good - I didn't find any stains, holes, or tears. There are a few snags to embroidery, but nothing major. I believe the 8" of fabric at the bottom of the slip dress was added by a former owner - it also looks like the slip dress was taken in along the side seams at some point - see closeup - that alteration cannot be undone. Shoulder straps were also shortened by about 1" and could be let back down.