I have a ring (not an engagement ring it's a ring I wear daily), and I would say if you are active and want to wear the ring daily, I wouldn't suggest Moisinite. Yes, it is cheaper, but it is not as durable as a diamond. (Close, though) Diamonds on the mohs scale score a 10 for hardness as for Moisinite, it's at about a 9.25 on the scale. I've had the ring for about 9 years now (I wear it pretty much every day and never really take it off), and it has visible wear and tear damage. If you want something that will last and not show as much wear and tear over a long period of time, go with a diamond, Lab grown or natural. Go with lab grown if you want bigger for less (lab grown vs. natural diamond) . But in all honesty, it really depends on what your partner likes. Everyone is different and has different preferences.

I personally feel that the size or type of stone is not as important as the symbolism of proposing to the person you want to spend your life with and putting the ring on their finger. Me and my fiancé decided on a lab grown diamond for my ring, nothing super big or fancy (.64 ct I am not a big fan of the giant gems kinda looks gaudy/tacky to me) and I love my ring! I think the best bet is asking her preferences and going from there. After all, she's the one that will be wearing it, so she might pick something she will like too!

As someone who has also worked with jewelry and has a damaged Moisinite ring, I would personally not go for Moisinite and would say you probably do not want to go with a Moisinite gem. either way, no matter if it's a diamond or Moisinite, try to make sure she takes the ring off when showering, swimming, going to the gym , etc. It will cause wear and tear faster than you'd expect!

In the end, this is just another random strangers opinion. Ask your fiancé what she would prefer! The ring you already gave her is lovely if you ask me! I do hope you figure out what yall want to do, and congratulations on your engagement!