Well shiny jewellery is just a minor application. Diamonds in ready supply means we could have 81 Gigahertz processors in our computers! For a cheap cost.... The fastest silicon processors melt out at around 10 gigahertz....
My mother gave my wife a synthetic ruby ring. It was worth a lot of money back when it was made. Now they don't even make it anymore. I gues they are visibly distinguishable from natural ruby, being too perfect.
In the case of diamond, this synthetic diamond will probably be as perfect as perfect diamond can be.
If they can be manufacturerd reasonably, it will totally devastate the diamond market. I did not think I would live to see this day.
Perhaps in the future, they will make costume jewelry from real diamonds.