You need to find somewhere inconspicuous (underneath the front or back?) where you can scratch the finish with a utility knife blade. If it's paint
, you'll be able to scratch it off, and probably see a different colour gel coat underneath, but if it's gel coat, the colour will remain the same.
Just getting underneath the ends, where any paint
preparation or application may not have been done well, may give you the answer without any scratching.
If there is paint
, and it's a perfect match for the gel coat colour, then it will be hard to tell!