I have a granite kitchen counter top that is uneven. The top is made up of two slabs. The slabs are uneven where they join at the grout line. Can I grind the slab and even it out and more importantly can I match the existing shine?

You can grind the uneven counter flat but, I would first check to see why the slabs are uneven. It is possible that the plywood under the slabs has shifted or the granite was installed uneven. Check to make sure the slabs are secure. After the granite is secure you can then grind the surfaces flat. Is it possible to match the existing shine? This will depend on the type of granite. If its black granite it will be difficult. The reds, salt and peppers are much easier to blend.

TIP When honing and polishing granite tops it is important to use as heavy a machine as possible. Also make sure you use diamonds designed for granite.