In kitchens where the cabinets are frameless or the dishwasher is low, or both, it is common to introduce an underlayment to the granite counter. This underlayment is a support made of either plywood or particleboard, which is laid across the top of the dishwasher, under the interior of the tops of the cabinets. Then the installer glues the granite counter with silicone onto the underlayment, as well as any front framework of the cabinets. This provides support to the stone, so if the dishwasher does not come up directly under the counter, there is no stress point on the stone.
One concern that some homeowners have is the heat and steam issuing from the dishwasher. On one hand, granite is an igneous rock that was formed of molten lava; the heat generated from the dishwasher will not harm the stone. On the other hand, some granites, particularly light-colored stones, are porous and may therefore absorb some moisture from the steam. If this occurs, it may temporarily darken the granite above the dishwasher. When the moisture evaporates, this darkness will dissipate, leaving the granite in its original color and condition. Most granite is not subject to extreme etching, so there should be no loss of shine.
For a dishwasher to function properly, you must attach it to the counter above. Dishwashers come with small mounting clips located at the top of the machine, and they're out of sight when the machine is pushed fully back under the counter. Because most granites will have a plywood or particleboard underlayment, it is possible to attach the dishwasher to the wood supporting the granite using screws. In the case of dishwashers mounted beneath a counter, you can attach the dishwasher the same way an undermount sink is attached; by using epoxy to secure the mounting clips to the underside of the granite.
The only time a dishwasher may cause a problem with the installation of a granite countertop is if the dishwasher is screwed into the stone itself. When using a plywood underlayment, it's important not to screw through the wood and into the stone itself. Likewise, if no plywood is installed, use epoxy to attach the dishwasher, rather than a bolt or drilled hole. If necessary, you can epoxy a small piece of plywood onto the bottom of the granite and attach the dishwasher to this, particularly if the dishwasher is likely to be replaced before the countertop.