What shapes are most likely to be damaged (chipped, etc.)? I know it depends on how they are set and the hardness, etc. of the stone but I''m not sure about the shape aspects.
There are no shapes which are inherently more prong to damage than others...provided the cutter rounds the very ends of those sharp points prior to setting the stones. It doesn''t take much, just a little rounding which is usually covered by chevrons, double prongs or even bezels. The setter can even do this with hand tools and a bit of diamond compound. That little rounding will increase the durability of those pointy stones dramatically, I just wish diamond cutters would clip the points on there pointy stones too !