I claim, the ornamental design for a vase, as shown and described.
FIG. 1 is a front perspective view of a vase, showing my new design;
FIG. 2 is a front elevation view thereof;
FIG. 3 is a rear elevation view thereof;
FIG. 4 is a left side elevation view thereof;
FIG. 5 is a right side elevation view thereof;
FIG. 6 is top plan view thereof; and,
FIG. 7 is a bottom plan view thereof; where second and third embodiments of the design are substantially identical to the design shown in the drawings but are translucent and transparent, respectively.