If you are in a committed relationship then you really should give him the chance to explain. I would tell him that you know and was wondering why he would tell you that it is real. He could have wanted the commitment and not had the money to buy you a ring or maybe he is cheap. But you want to know because if you are thinking of leaving then you should want to know why he did this. If it was because he didn't have enough money that is much different than cheap. You at least know you were marrying someone cheap. I would confront him but not in an angry way. There could be a rational explanation. After you get all this information then I would decide if his love can be measured in a fake ring. That is something you should talk about too. It is disheartening to get engaged with a fake ring. See if his feelings are more than the fake gold when you talk to him. Make your decision from this talk. Definitely bring it up.
If this is helpful press accept