I know one lovely lady told her man that the ring he first proposed with wasn't gonna fly, of course she didn't tell him that when he proposed but sure enough the first ring disappeared and was replaced with a larger fabulous one.
As women we dream about the rock, we shop for the rock- often times before we have the Right Man! So would you put a contingency on your I Do? There is so much marketing pushing us into believing the bigger the rock the better the man (and bank- lol)
Well my two cents for you- be more concerned about the size of his heart rather than the rock he proposes to you with!