A very nice Bulova Mignon. Checking the adverts on this site, the Mignon seems to be the first model to have black enamel inlay. The bezel has the number 283 imprinted, that corresponds with the case serial number on the back.
A nice detail: in the advert of 11 December 1926 you find the Mignon underneath the Theodora, a watch I am lucky to also own.
The size is 15mm wide by 24mm long.
I purposely chose a lighter color strap to have the black enamel stand out.