is my pot damaged?
I noticed that the inside bottom of my new Lagostina pot is rainbowy (I've used it for about three months) ... does that mean its damaged? .. what causes that? please help.
Your pot is fine. Most stainless will do that when heated a bit too high. Get a can of Barkeepers Friend and it will come right off, and be good as new!. It's great as a general cleaner for stainless when just dish soap isn't enough, and it's very inexpensive too. You might also try heating a bit of white vinegar in water in it, or just wiping it out with that.
Blondelle is correct, your pot is 110% OK. In fact, if I were you, I would do absolutely nothing to the pan and keep cooking with it. Those harmless 'rainbows' tend to come and go and I would even hesitate to say that you've cooked at too high a temperature. It's just the nature of SS. Save your Barkeeper's Friend and vinegar for something else.
Yea unfortunately stainless, stains. What a contradiction in terms ;) I recently got a commercial grade frying pan, and the same thing happened to it. I got a rainbow looking mark on my pan bottom.
Happens all the time to my stainless steel pots and pans, regardless of quality. I associate it with cooking starchy foods, rather than with using high heat. But in any case, it doesn't bother me and I don't do anything about it. As blondelle says, Barkeeper's Friend will remove the rainbows. Otherwise, they'll probably go away the next time you use the pot for something mildly acidic, such as tomato sauce.