Does a zirconium crown start showing metal on the gum line? (Photo)

I have a bridge of 3 crowns, front teeth. I recently got them replaced ( 2 years ago). I was told the metal wont show on the gum line but after 2 years it has started to show. I paid a very large sum to get it done and thought it would last atleast 10 years. In the snapshot below you cannot really make out the metal line but its there on 2 of the 3 crowns. Did the dentist lie about using metal? or is this going to happen with any crowns i get.