[ridgeguy]

Thanks for your informative comment. I know less about HPHT diamond synthesis, and may not understand the cost structure of that technology as well as I would like.

I agree re the current high capital cost of CVD diamond synthesis equipment, but I'm pretty certain it need not remain so. For example, in microwave plasma assisted diamond CVD, significant slices of the cost pie are in the microwave power source and the deposition chamber. The former tends not to take advantage of 2.45 GHz consumer sources and is, I think, overpriced in $/Watt compared to what it could be with some additional electronic design work. The latter suffers because diamond microwave CVD chambers tend to be one-offs. Building them in hundreds or thousands would allow lower cost manufacturing technologies to be used.

Power costs are an issue, but there are ways of extending the lifetime of atomic hydrogen, which is a key cost determinant of CVD diamond. Labor costs will be reducible to the extent that CVD processes can be automated, which I regard as largely a matter of getting reproducible processes in hand. When you have a predictable process, you can automate it.

I concur it will be awhile before my Replicator 2 can spit out a diamond filament. But I think the current manufacturing cost of diamonds is far higher than what it might be. The missing link is somebody willing to fund the volume manufacturing process development.