"an upgrade to a diamond was demanded, on threat of divorce"
this sounds like the opposite of a true marriage to me.
*But of course I have no idea about your lives and wish you the very best.
Meanwhile, my wife and I have not even worn rings for years, and no plan on the table to get new ones. Initially it was caused because we went through a very rough patch and we both were giving up on the marriage. But that turned around, and now years later the work we've done in our marriage stands on its own, and the rings are only a reminder of the shredded remains of the old marriage. So we don't wear them.
(It's fun to have this conversation with gender-neutral pronouns.)