For this kind of stain use a specially formulated granite cleaning product like granite gold daily cleaner and scrub with a soft bristled brush then rinse and dry with a soft cloth.
White rings around faucet on granite.
These are formed by the water that flows into the home and is fairly common in most cities.
Hard water stains around the faucet.
A water filter may not be sufficient to deal with hard water.
You can also use a single edge razor blade to gently scrape away the residue or a safe on stone pad to scrub the area softly before rinsing and drying.
The ugly white or yellowish rings around the faucet base aren t unusual.
For really stubborn stains try using a poultice or extractor.
Poultice products made especially for granite can be purchased at a hardware or stone surface specialty store or you can make your own paste using flour plus hydrogen peroxide.
For those tenacious water rings around a faucet resulting from hard water that sits on the surface try scrubbing softly with a brillo pad or gently scraping with a razor blade then wiping away the residue with a soft damp cloth.
You need a water softening system.
Scrub the granite sink with the scrubbing pad.
Rinse the granite sink thoroughly with hot water.
Hard water can create a calcium buildup which is also called limescale or lime deposits.
There was a thread here a few weeks months ago about a similar sounding situation.
And your hard water may be contributing as well.
Maybe they used plummer s putty at your faucet connections.
Dampen a nonabrasive scrubbing pad with water and apply 2 or 3 drops of mild dish detergent.
I get that they do not sit directly on the granite but soapy water certainly does get onto the granite particularly around the soap bottle and sponge.