Vintage circa 1920s French waistcoat.
 
White waffle cotton with part shawl collar and four real mother of pearl buttons to fasten.  The lining and back are made from what feels like silk but could easily be rayon. Two lower slip pockets.
 
No maker's label or size label on this- please refer to the measurements at the bottom of the listing ⬇️ and do note the flaws mentioned. 
 
Small brownish stain on the shoulder and front- see photos, there are some scattered brown rust type marks - at the back section, on the cinch belt and around the cinch belt, by the front collar at the base. The back buckle has rusted. There are brown spots at the pockets and at the nape edge.  Some grazing  and a few small holes on the silky lining and at the back section.
See photos. 
 

Seam to seam across the shoulders at the back is 14 3/4"
21" total back length
Across the chest under the arms is 18 1/2" -  pit to pit, across the front
19" across the bottom edge, side to side
From the centre point of the v  at the front to the bottom edge is 9"