A lot of the good quality cookware ranges really try to hedge their bets on the issue of whether the pans can be put in the dishwasher.

Most of the are "Dishwasher Safe" so you pan will not literally fall to pieces in the dishwasher, but most manufacturers recommend that hand washing with hot soapy water and a non abrasive scourer is better.

This is because caustic detergents can long term, damage the non stick surface. It does all depend what quality of detergent you use, but manufacturers like Swiss Diamond or Gastrolux, for example, suggest hand wash only is the best care you can give them.

In terms of the warranty, to be honest, I am not clear how the manufacturers will react to a pan with a non stick surface damaged by caustic detergents due to dishwasher use. I suspect it will be a grey area of to-ing and fro-ing rather than a clear warranty claim.

One the bright side, I have had no claims of this kind at all so far, and Gastrolux, for example, have been absolutely excellent on giving the customer the benefit of the doubt on warranty claims.

NB I have to say, that personally, I hand wash my expensive pans. Why risk reducing their life expectancy?