Selling diamond engagement rings to online store will surely help you to bag a good deal. However, you will need to submit the grading report of your ring to the store or buyer, so that they can determine the exact value of the diamond engagement ring. If you do not have any such documents with you, then you might not be able to get a good price for the ring.
If you do not like the idea of selling diamond engagement rings online, then it is best to approach a reputed diamond dealer. The issue with this is that the price offered by most diamond dealers will be relatively low. Yet if your old diamond engagement ring belonged to a specific era that categorizes it as a vintage jewelry piece, then you will surely get a great value for it.