The problem with man made diamonds is that like any technology, they'll get progressively cheaper as the production technology gets better. We saw that in a huge way when De Beers rolled out their Lightbox line and undercut pretty much everyone.
It’s a problem if you want to consider something such a nice jewelry or a wedding ring as an investment. I would guess that some people buy the real thing because it’s less likely to lose its value over time?
I'm not sure what you mean by "less likely to lose its value over time". If you buy a natural diamond in retail it lost more than half its value the moment you bought it. (it was never worth the retail price to begin with) As an investment, it's a terrible idea.
I'm not saying it's a good investment, to be clear I know absolutely nothing about diamonds. I was just sharing a potential reason why people may favor natural ones over manufactured ones. If the process to make synthesized diamonds becomes cheaper faster than a natural diamond lose its value, then you might be better off with the natural one if you consider it strictly from an investment point of view. Losing 50% of its value after purchase may be better than losing an potentially more after a few years once the industry figured out a way to manufacture diamonds at a way lower cost.
