This is a pot de creme cup produced by Richard Ginori, Italy in the pattern Primavera (spring). The cup uses the Ginori older "squat" style cup. The colors are spring-like soft pastels of pink, blue, green and yellow. The front of the cup has a different color motif from the the back.
The cups were produced in the 1960's to the 1970's. Richard Ginori is one of the few porcelain manufacturers that still produces pots de creme cups today.
The mark is the Ginori crown in green with the bold yellow over-stamp with black writing (see images). There is also a paper label showing the pattern name.