If scratches aren't an issue, diagonal side cutters work a lot better than needle nose pliers. Just be careful not to over-tighten!
Oh, and some Gerber pivot bolts only turn freely on one side, so try each side gently to figure out which one spins. My bet would be the side with the retainer ring, but I am not sure. Maybe someone else will know a trick or two, but I have luckily not needed to tighten my CD.