I have been receiving several requests lately regarding sinks separating or failing from granite countertops. These were all undermount sinks that were originally installed incorrectly because they were missing brackets or perhaps the glue was not left to dry overnight. The fix for this situation is a two day process. First, all the plumbing must be disconmected and the sink removed. Then the glue than remains on the sink and granite must be cleaned off. A special epoxy is then mixed and applied to the sink and it is replaced and clamped for 24 hours. Brackets are also installed. The next day the faucet, dishwasher, disposal are all reinstalled. As you can see, this is quite a process for what appears to be a small problem. Your best bet is to have a reliable team install your granite the first time so this problem does not happen later.