bicyclegirl1:
I'm assuming your sink is undermounted? If so, can you slid a steak knife between the sink flange and the bottom of the stone? Is there a recurring brown gunk there? Can you press on your sink divider and pump water from the gap?
If you have any of these symptoms, your sink is leaking and retaining water between the sink flange and the stone bottom. It is not only horribly unsanitary, it is discoloring your stone.
Were you my customer and the sink was leaking, I'd drop your sink and come back a week or so later when the stone dried out and strap it in place after sealing. No more leaking, no more discoloration.
Do not apply topical sealer before the discoloration is gone, please.
Q
joseph corlett comments on greying of sink.
Q