Picture please.

Ive got the same thing on my kohler bath sinks. It is a blue circle around the drain. Mine sinks are Kohler Caxton. It happened to my two masterbath sinks and the second bath sink. The powder room is fine.

@Minardi That does make complete sense for my situation but I think the color may be coming from my faucets. The 3 sinks that have this blueish green ring around the drain have the same faucet while my powder room has no ring and has a different faucet. I also noticed that the blueish green rings are different sizes in each sink and it coincides with the amount of water that sits around the drain after using the sinks. We are on well water and I measured the Ph and it is 6.5.

problem solved, for now, with of "Soft Scrub All Purpose Commercial Cleanser , with Lemon". Let it sit for awhille -wipe down .

6.5 is on the lower end of what is considered good. I'd try to increase the Ph with a filter with calcium carbonate or similar and you can increase the Ph by about 1 point and protect those copper pipes

@just_janni I do not have copper pipes. I think the color is coming from my faucets.