Ah, but the rarity of this ring is that it is GOLD.

This was at a time when gold was, well, worth it's weight in gold. The only ones that could afford a gold ring were those of wealth: nobility, royalty, high ranking church and military members, and, of course, rich merchants. Wedding rings of that era were often made iof Iron so they wouldn't be destroyed when the lady of the house cleaned, cooked and did other various chores around the place.