Man I hate fragging. I've had the worst luck but a few days ago I finally got it. Batteries die (big mistake, should have gotten corded dremel), mandel too small for the large diamond bit, my buddy drew a little blood. I thought I had it down the other day and made some good cuts going right over the top (had to because of the rocks they were on) and last night as I was checking healing - I realized I reeeeaaally screwed up. I had a 25 polyp colong of Pink Floyd and I cut the top off, about 10 polyps so I could keep the top 10 and remount smaller frags of the rest - and I left the other 15 polyps out!!! I was so panicky trying to get things back in the tank I forgot about the mother. The ring of 15 is a goner but I did get a nice big 10-12 frag mounted flush on a disc for growth.
Fortunately I didn't do the same thing with my P Lem colony (which I like much more) - I got a good cut off the top of about 10 polyps and have a ring of about 20 polyps left I can remount after I cut them up into several frags. They were on a rock that pretty much ended any future growth so I had to.
The learning curve was super steep for me and I made a lot of mistakes but hopefully I have it down now. I didn't use Lugols but thats a great tip Doc, I wish I would have.