This pure milk white glass cup and saucer set made by Hazel Atlas were sold as Espresso or Demitasse sets. They were sometimes sold decorated with a painted design but most often found in the solid white which the Hazel Atlas Company referred to as Platonite.
The cup and saucer set is the same size that were sold with fired on colors in some of the kiddie tea sets. Approximately 2 1/16" tall with a 4 1/2" saucer. Perfect for your Espresso or for tea with a little girl's favorite doll. As is frequently the case with Hazel Atlas, the logo is not present.
Cup and Saucers like this are pictured on page 83 of Gene Florence's book; The Hazel Atlas Identification and Value Guide.