You do know the diamond is going to be a harder playing table than the gc, right?
It WILL make you play worse and hopefully return to your natural level eventually...where you currently are.
Thats a common occurrence, to have the better player claim the worse one has no heart coz he wont take the short end of the stick.
Often accompanied by a side of 'bet some real money'.
Good moves, if he can get away with em🙄