I’m broke but need a ring ?

My boyfriend plans on proposing to me In the next year but we are on a very tight budget. I’d like to have a pretty enough ring that will last forever though. It doesn’t need to be super extravagant or expensive of course. I really like the look of sapphires or emeralds as the gem instead of diamonds so that’s good.

I don’t know what cheaper websites are reputable so I’m super interested in receiving links or names of places.

I’d also like to know any places to AVOID or any suggestions anyone might have? I’m just starting this journey so please feel free to give me any advice!