A pearl ball has a mica additive in the resin that stiffens the coverstock.  This stiffer cover provides less surface in contact with the lane, resulting in less friction and the usual pearl "clean through the heads" reaction.  Large bits of mica were used as an early type of particle, but the usual meaning of "pearl" means a finely ground dust or powder, not really chunky or gritty.

Sanding a pearl will do pretty much the same thing that sanding a solid or particle ball will have.  More friction, earlier roll, less backend, smoother reaction.  How much of an effect depends on the coverstock and the sanding grit.

SH