Hole in granite countertop for kitchen faucet slightly small
Two things:

Do not do this yourself.   The other answer is technically right but I would only do that if there was no hole.   Either call up the place you got the granite from or another installer (which may run you $30-75).   The issue is that once you start drilling and your bit catches the edge of the hole already there it will skip.   Once it skip you can get chips or cracking.   One of the harder tradesman things I can think of is making a hole slightly bigger.   If you are going to do it yourself then sand it out with a dremel (which might take a while, yet won't damage.

Make it 1.5&quot; so that you future-proof this.   I don't understand unless if it was a bathroom vanity why it wouldn't be 1.5&quot; but that has been the standard for 15+ years for all kitchen sinks.   I know guys that do 2&quot;.   I wouldn't go 2&quot; as that will require a cap (for the capless faucets) but 1.5&quot; is safe and will allow you to buy 98% of the faucets out there.


Note:   I really despise the &quot;have someone else do it answers&quot;.   But there are three things here - first just to do it yourself it will quite possibly be more expensive.   Second you may never use this diamond bit again.   Third you are talking about messing something up that is 1/30th of the cost to drill the hole bigger.   The risk vs reward doing it yourself doesn't make sense.