This is what I would do/ I do lol. Find the nearest LFS and call them. Ask them if they can frag your coral with a band saw. Most shops are super cool and will do it for free. If they don’t do it for free, then move on 2 the next LFS and ask them LOL. Jk offer to give them a $5-$10 tip for doing it. That way you can get a nice clean cut and don’t lose any of the coral On the rock/ frag plug or plate. Also if the LFS is SUPER COOL they might give you a Frag plug or plate to put the newly cut coral on.