I got an implant in my front top tooth about 6 months ago. How long should my gums be bruised after?

A picture would be helpful to determine. Very unlikely that it’s still bruising after 6 months. This discoloration maybe due to the metal or dental implant color showing through your gum tissue. depending on the position where the implant is placed, it maybe placed too close to the surface of your gum tissue. See your dentist/oral surgeon/periodontist that placed this implant for an evaluation.