Hi, the question of "what's the best cut to use for my gems if I want to cut them for money" has been bugging me for some time now, and since I couldn't find what I was looking for, I did some math. Now I thought I might as well share the results.
I did not really consider transfiguration. (I think going for soulpieces, than tiberium and finally nectar might be best, but I didn't do the math on that as I can't find the script that runs transfiguration). (And in case you were wondering about skull cuts, since you have to use eight gems for that, the profit per gem mostly sucks. You could get lucky using different types of gems, but unless you use save-reload cheese, it's not worth it).
Have very low value gems cut might be worth it if the chance to get a Mysterious Mr. Gnome is high enough, but since I don't know that chance, ....
Anyway, I took into account the value multiplicators in the guide, the cost of the cuts, and the loss of the uncut gem. This is what I got:
Gems up to $40 are best sold raw. Unless you want better cuts quickly.
oval from $41 to $60
plumbbob from $60 to $83
crystal Ball from $84 to $166
brilliant from $167 to $500
and finally heart shaped for $500 and everything above.
For septeria, heart shaped takes the lead from $386 on.