I read an almost exact accounting of the S&W Carbonia story on another website some time back.
I will have to look for it as it had more details on period finishes and recipes for those finishes.
Colt offered a limited edition WWI 1911 a few years back advertised with a Carbonia finish.
As the story goes they sent them out to be Carbonia finished outside their factory by a private gunsmith,
So although Colt has offered handguns for sale that were advertised as finished in Carbonia ,
They did not perform the actual finish and because the true recipe was lost the term
"Carbonia Finish" will always be disputed.
This is a side by side picture of their "Carbonia style" finished 1911 next to a parkerized 1911 for comparison.