IT DOESNT WORK LIKE INTENDED !! ITS A BUG I BUY THE GOLD ITEM AND THE GAME BUY ME THE DIAMOND ONE
I'm sorry but I don't think that is what happened. You probably clicked the diamond item by mistake... The game has been going on for years and no one ever reported what you're saying.
With that said, I think Lilith could, and probably should, be kind enough to give you your diamonds back and remove the item from your inventory. It's obvious that you didn't want to spend hard earned diamonds on a crappy item... And they lose nothing by doing this. I think keeping the customers happy is good for business.