I would like to point out that the quality of the ring and the quality of the marriage have nothing to do with each other! When I got enganged I was not able to afford a diamond so I got my wife a silver ring that I knew she would like and that I could afford.
Also you can always upgrade the ring later if you are in a better shape!
On the other hand telling her that a ring is real when its not is a really bad start to things.