Other People’s Problems: Recycling A Ring

I am in love with a wonderful woman and about to propose while we’re in McCall for 4th of July weekend. I have a whole plan with a fireworks display and lights that will spell out “will you marry me?”. She has NO idea that it’s coming. She has been dropping hints for the past couple of months about what type of ring she wants and ideas for our wedding. The question I have is, I was previously engaged and planned on using the engagement ring that once belonged to my ex-fiance. She returned it after we broke up and it’s been sitting in a box in my closet for 3 years. My family and good friends are the only ones that know that the ring is used and I’ve been getting half saying “that’s great!” and the other half saying “you can’t do that!” Is there anything wrong with recycling the ring?