You might try reading this:
Late-War Luftwaffe Fighter Camouflage - Part Three
Commentary on the Evolution and Usage of Luftwaffe RLM Colours 81, 82 83
By David E. Brown
here's the link:
Luftwaffe Late War Fighter Camouflage - Part Three
Quotes from the article:
1) No official documents have been discovered which link RLM 83 with the colour name "Dunkelgrün". However, Hitchcock (1983, p.13) states: "Color 83 has been officially recorded as 'green.' " but fails to identify the source, date and context of this official record. The relationship of "83" to the descriptive name "Dunkelgrün" is interpretive, and based on photographs, crash reports, wreckage fragments, etc. (Smith and Creek, 1994, p.247; Smith and Gallaspy, 1977, pp.96, 100, 124-125, 129, 134, 13-137)).
2) From the data, the name "Dunkelgrün" was assigned to no less than four defined colours; first to RLM 71 in 1937 and later in 1944 to RLM 81, 82 and 83. There is no question that the RLM designated 71 as Dunkelgrün, but did it also do the same for the remaining three colours? Given the RLM's past history and actions, the evidence strongly suggests that it did not.
That being said, I've always taken RLM 83 as dark green as well and in addition to Steve's links, I have at least three more that also show RLM 83 as a dark green.
Interestingly, the ONE source that shows both a Green FS 34138 and Dark Green FS 34083 color for RLM 83 is the IPMS stockholm color chart.
Link:
Color Reference Charts - Germany