What evidence? Obviously, there will always be variations but the processes are easily grouped. The fact that Colt has a special name for their "Royal Blue" does not change the fact that it is a hot salt process. The fact that Colt and S&W used different ingredients and levels of polish does not change the fact that the two processes fall under "charcoal blue". Or what is also referred to by current professionals Doug Turnbull and Hamilton Bowen as "carbona". What USFA refers to as "Armory blue". The fact that Turnbull's and Colt's color case hardening differ from each other in end result does not change the fact that they are still variations of the same process. Same for cyanide case coloring. I have never argued that the results of any of these processes was the same, that the color was the same or that the level of polish was the same, only that the processes themselves were similar enough to be grouped together by anybody you ask. Unless you consider Bowen and Turnbull to be morons. Now if what Turnbull and Bowen refer to as charcoal/carbona blue is different from what Colt used to do, that is not my problem. Since Ole Fluffer has decided to either keep the information to himself or simply does not possess the information and since the information is apparently readily available, I invite anyone to offer up "evidence".
All of which is completely tangent to the discussion. The fact remains that there is no reason why S&W can't offer a finish like the above-pictured USFA, which is superior in every way to any of my alleged "Carbonia"-finished S&W's. Charcoal blue, antique or modern, is a different animal entirely. However, I would also like to point out that in Turnbull's fee schedule, there is only a $100 increase for charcoal over hot salt blue.