Times and styles change, jewellery does wear down, especially when two rings are worn together. The tradition of wearing an engagement and wedding ring together does over the years cause damage to both.
Sometimes they can be restored.
I trained in London in the delicate art of antique restoration, a highly specialised field in the jewellery industry. Knowing how to make a piece of jewellery as it was originally made is the key to restoration.
If caught in time, your precious heirloom can be restored to its former glory.