The vase can be printed in vase-mode (In Cura: Spiralize Outer Contour) to get a perfect clean surface. To get it watertight, depending on the print-size, you might use a bigger nozzle like 0.4 or 0.6.
A high quality HD version with over 1 mio triangles is also included:
SpiralVase.stl 219_478 triangles
SpiralVase-HD.stl 1_348_624 triangles
SpiralVase-hollow.stl hollowed with 1.49 mm shell (0.058 inches)