This is a stunning vase. The glaze is so smooth and glass like it defies being photographed. 5 inches tall. The color is somewhat of a green near the top and proceeds smoothly to get bluer and darker towards the bottom. The drip look in the picture is a reflection. It almost perfectly captures the look of a calm ocean on a sunny day. There are crystals, blue in the glaze, most near the top. There is one medium size star burst crystal in the middle of the vase as shown. I do not recognize the mark (no it is not Rookwood). I expect this is a studio piece, and probably european (the 13 on the bottom probably indicates 13 cm), and probably less that 5 years old. The vase is somewhat lighter than the pictures. It appears to be hand thrown, and perfectly so.
Information provided by Ron and Liz leads me to think this is a vase by studio potter Rosslyn Reed. Thank you for the help.