Diamonds are the most over rated gems in existence. The notion of their rarity was fabricated to inflate their price; it is one of the most common gems, to the point there are places in our solar system where it rains diamonds. And even on Earth, the existing reserves are very carefully controlled to ensure prices do not drop because if it were to be commercially escavated at full capacity, it would flood and dunk the market, permanently.

So finding other uses for pure carbon gems is a plus, although the ones going into this use will certainly be synthetic ones.