Matte Blue Glazed Art Pottery Vase with Sylized Lip

I just love the lines of this art pottery vase, reminding me a bit of the the petals of a tulip opening. Glazed a striking, bold blue, It's the perfect size and shape for an everyday vase, and everything looks good in it--though with such an elegant sculptural form,  it's also great holding nothing at all!  Unsigned, but with a round mark on the bottom, I believe this vase is American, circa 1930s-50s. 

8 1/2" tall x 4 1/4" wide x 3 3/4" deep and in excellent condition, with no visible flaws whatsoever.