I claim the ornamental design for a perfume diffuser, as shown and described.
FIG. 1 is an isometric view of a perfume diffuser showing my new design.
FIG. 2 is a side view of the perfume diffuser shown in FIG. 1.
FIG. 3 is a top view of the perfume diffuser shown in FIG. 1; and,
FIG. 4 is an end view of the perfume diffuser shown in FIG. 1.
The broken lines are provided for illustrative purposes only, and form no part of the claimed design. In addition, the portions of the perfume diffuser that are not shown in the drawing do not form any part of the claimed design.