I purchased these mugs because when I visited my sister she had a set and I absolutely loved them. I ordered a set of four and after my first time using them I noticed some dark spots on just one of the mugs. I took a few pictures and sent them to Benicci customer service. They responded within two hours and asked if I would like a refund or a replacement. Of course I wanted the replacement. The same day they emailed me staying the replacement mugs were on their way. Exceptional customer service and beautifully designed mugs.