Is there only one version of a Gatekey?

I'm not really sure if there is I have watched many different anime shows but the only time I have actually seen Gatekeys was in Fairy Tail because Lucy has them and there are 12 different Gatekeys 6 silver ones and 6 gold one. Watch Fairy Tail and you will see them. I <3 <3 <3 Fairy Tail.