I questioned the color when my granite was installed?

You do have rights as you weren't told at point of sale that you might get a different colour even if it's slightly different. It's worth pursuing as you have spent a lot of money on somerhing that isn't the right colour.

Never buy granite from samples or pictures as slabs do differ. The deeper they go into the hill or mountain the more the grain and color change. Most places have slabs on site and let you pick the actual slab you want then put your name on it. That's the only way to buy granite. Small samples will never give you a true picture of what you're going to get.

You should have never let them install the wrong granite. I suspect you are stuck here. You should have refused delivery of the granite. Now it seems like you changed your mind. It's not worth it to hire a lawyer... It's going to be very difficult to prove they gave you a different type of granite than what you paid you.

Also if you are selling the house and people like it... what's the problem?

So, you are selling the house and the potential buyers like it? Get over it and move on. Next time you need granite, go somewhere else and work with someone who will let you select the actual pieces of granite your counter top will be cut from.

A quality installer will always have the buyer select the actual piece of granite so there is no question as to what you are getting.