My DH has offered to upgrade my engagement ring. I currently have a 1.67 center stone (H, S1) with two side stones totaling 1.34 (G, VS1). All three stones are round. In order to make the upgrade worth it, what would you guess is the minimum carat weight I would need to notice a difference? IS 2.5 carats for the center going to be large enough? Does anyone have pics of three rounds with a total weight larger than 3 carats. thanks