This was under the dish drainer
Does the water pool, and is it leaving the ring only after you wipe it off? I learned about sealing granite a few years ago and they advise you to test by putting a small amount of water on various parts of your granite. If the granite darkens, because of water penetration, then your granite needs sealant.
looks like you have hard water.
I need to be the one writing their instruction sheet: “It’s good to keep an eye out for potential problems with your new countertops (but please do remember to return your eye to its socket). The countertops we’ve installed for you are very durable, but it’s best not to take things for granite.”
OK, actually let someone else write it.