Thank you for posting this!!!! I have the same situation and have thought about this alot, so stick with me, I have alot of points….
1. You need to be happy with something you are going to be wearing for the rest of your life because no matter what people tell you about trading in or up, if you do, you are going to loose ALOT of money!!!! Sadly diamonds do not maintain their value. So make sure you are getting what you want.
2. Intrest alone could be the diffrence between your dream ring, dont believe me, add it up. So think about saving up first before you buy and put that extra money towards your rock!
3. Do not buy from a jewlery store!!!!! Buy from James Allen, enchanted diamonds, blue nile or a pawn shop, they are half the price of a retail store.
4. Diamonds are a bad investment, it doesn’t mean you shouldn’t get one, but that is a fact you should know before you put money into one. They cost a bunch of money, and you can not get that amount back, also you usally have to buy a lower quality then you’d like to have. So consider diamond alternatives like Forever one Moissanite or Amora gem Ultra and the left over money you could put in a bond, toward a house, on the wedding, vacation, car, etc. I am still struggling with that choice myself, because I want to make a smart decision and also have an amazing stone but social pressure to get a diamond is a Be-och!
5. Finally, if you want add money to buy a nicer stone I think he should not have a problem with it, because obviously it is important to you or you wouldn’t have posted, its okay to spurlge on something you will be wearing everyday for years. He especially should be fine if he is paying for most of the ring. Just be sure that you make it clear you’d be happy with what he can get but this is something you really want and explain the giant downside to trying to trade up later, so it is smarter for you to buy the size you want now.
Goodluck I hope something helped!!! I myself never thought picking a ring would be so hard or expensive, and I blame the movies where middle class people buy giant diamonds of perfection!!!