Mutant gem used in place 2016 gem

Kohli1999

I have a colossus at rank 3
And I tried to use rank 3-4 gem on him (2016) version but it used up my murant rank 3-4 gem

Kabam Zibiit

Hey there, our Support Team would be best equipped to look into this for you. You can reach them from the game's home screen by clicking the gear-shaped icon in the top-left corner of the screen and then scrolling down to the button labeled "Support".