The answer may depend on whether the ring was an outright gift or a conditional gift given in contemplation of marriage. If it was an outright gift – it’s yours! However, there is little case law in Alabama regarding gifts given in contemplation of marriage. If the ring was given as a symbol of the promise to marry, with the acceptance of the ring be conditioned on the actual follow through of the marriage, then he would most likely be entitled to receive the ring back.
This is the general rule:
If he proposed to you on a random day, it is his property and you must give it back. If he proposed to you on your birthday, Christmas, etc., you have a strong argument that the ring is a gift and you can keep it. If he agrees to let you keep the ring in exchange for something else, you can keep the ring.
Some states have specific case law on topic, and I am not aware of Alabama's stance. Not only did we learn the above rule in law school, but I learned this scenario from a failed engagement. Good luck.