The ornamental design for gel candle, as shown and described.
FIG. 1 is a top perspective view gel candle showing my new design, wherein wine corks are disposed in a slanted fashion within a votive vessel and a first unclaimed material is disposed on a bottom portion of the votive vessel.
FIG. 2 is a side perspective view thereof; and,
FIG. 3 is a side perspective view of the gel candle, wherein a second unclaimed material is disposed on a bottom portion of the votive vessel.
The single dashed lines represent outer portions of a gel candle, an inner vessel and a wick and form no part of the claim. The characteristic feature of the design resides with the gel candle having materials embedded therein.