A certificate describing a single 1/3 carat stone from ten years ago is evidence. Few would call that proof, as such.
Proof would consist of a number of criteria like trusted witnesses, repeatability and reproducibility, not to mention significant experimental production.
I think Magnatek works. I haven't seen enough to say I know it works. Likewise, the market does not yet consider this investment sufficiently de-risked enough to make even sensible projections.