My wife lost the diamond in her wedding ring and we were talking about getting it replaced. I have two daughters in their early 20s and they were aghast at the idea of replacing it with another diamond. They were adamant that nobody should buy diamonds for jewelry and instead should use a synthetic stone. They claim that "everyone" (which apparently means everyone they are in contact with on social media) knows this. If this kind of thinking really is widespread among the younger set then I'm not surprised that the demand is dropping.