All Right, here is the scoop.
Diamondcote is not available via smiths, dealers or any other channel except the Colorado School of Trades.
The Colorado School of Trades will take guns on a select basis, however there are some fairly strict rules.
The gun has to be spotless clean. They will not clean your gun for you. If there is an existing coating other than blueing it will cost more to have it removed. No S&W semi autos allowed because S&W bonds plastic parts to metal parts and this is incompatable with the application process.
The lead time takes 6 to 8 months! Diamondcote can not give you a progress report on your gun and neither can Colorado School of Trades. Don't call em cause they just can't tell. But you will get your gun shipped back to you within 48 hours of it arriving back from the coating process.
I am reliably informed that the latest process has indeed been perfected, that the end result is nearly black (very dark grey) and it is both beautiful and very durable.
I have a dark grey HP that is just beautiful and it has held up without a flaw in a years worth of field use and some range use. Mine was BC'd nearly one year ago.
If you have the time and the patience, I would highly recommend BC. If not, another avenue may be a better choice.