Well yes and no, it's carbon for sure but not the black carbon type instead it looks like pulverised glass because it's still in a crystaline form. Diamonds are more valuable the larger and more perfect they are because large perfect diamonds are rare. I've bought small diamonds retail for $15 because they are common. The diamond I'm talking about is slivers of pure crystaline diamond only 0.1mm thick (or less) which after forceful removal from a transistor would be like sandpaper grit which is what some diamond dust is used for.
The use of biological systems or materials to recover valuable resources from the recycling stream is an admirable objective. However, I'd predict they won't be adopted until they offer a high percentage recovery rate. In parallel, I suggest redoubling the effort to develop a closed loop recovery process. Even if the materials used to recover the gold are toxic, if they are reused and not released into the environment then the result may prove quite acceptable.