I have had some emails on this subject, and some questions on other forums, so I thought I would create this to link to so the questions can be answered more easily by simply referring the questioner to this page.
For a full discussion of this knife and scabbard variations, you may refer to Frank Trzaska's article entitled The Post War Combat Mark 2 in the January 2005 issue of Knife World. Back copies may be obtained (I believe) from http://www.knifeworld.com/
The subject here is the difference in color of the leather handles and scabbards of this knife.
In the photo to the right is the earliest production by Utica Cutlery circa 1961. This version pretty much followed the old WW2 specifications for the USMC knife 1219c2e and the USN Mark 2 (394831). It has the brown/tan scabbard and handle, curved guard, and 9 rivet scabbard. As far as I know, only the early Utica production followed this standard.
By the time Camillus entered production a year or so later, the specification had been changed to the straight guard, 7 rivet scabbard, and "black" leather. However, this color was not a true black, but is known by collectors as "Oxblood" and is a very dark slightly reddish brown. This color can best be seen in a bright light, preferably sunlight. This color can be found on later Utica, Camillus and Conetta production.
By 1980 the color specification had been changed again to a true black. Late Camillus, MSI, and Ontario production are usually found with the true black scabbard and handle. At least in Camillus, the change occurred over time, and black scabbards can be found with oxblood handles in original production.
In the photo below (and this was the cause of my writing all this in the first place as I was trying to get a photo to show the color variation), the left is the early Utica, the middle a Conetta in oxblood and the right a black Ontario. The light was daylight, very bright, and the colors are actually somewhat lighter than reality. Indoor and dimmer lighting may make it difficult to tell the oxblood from the black.
Edited by bayonetman, 20 March 2015 - 03:17 PM.