German Thread on the topic.
I'm translating it right now.
It seems to be somewhat depending on the ship, but roughly the same:
Nova Vanguard
- 0 - Red
- 20 - Orange
- 40 - Orange/Yellow
- 50 - Yellow
- 60 - Yellow/Green
- 70 - light green
- 90 - Green
- 120 - green blue
- 180 - light blue
- 200 - Blue
- 220 - dark blue
- 240 - Purple
- 250 - "
- 260 - "
- 270 - light purple
- 300 - pink
- 360 - Red
Kha'ak Bomber
- 0 - Purple
- 20 - pink
- 40 - light pink
- 50-70 - "
- 80 - Pink - Orange
- 90 - Orange - Pink
- 100 - Orange
- 120 - Orange/Yellow
- 130 - Yellow
- 150 - Yellow/Green
- 160 - Green/Yellow
- 180 - light green
- 200 - lime green
- 240 - light green/light blue
- 260 - greenish light blue
- 280 - light blue
- 300 - Blue
- 320 - blue/purple
- 340 - purple/blue
- 360 - Purple
Split Raptor
- 0 - redish brown/orange - normal split color sheme
- 20 - Orange
- 40-50 - Yellow
- 60-70 - Green/Yellow
- 80-150 - Green
- 160 - Green/Blue
- 180 - turquoise
- 200 - Blue
- 240 - dark blue
- 260 - dark purple
- 280 - Purple
- 300 - still purple
- 320 - Purple/Red
- 340 - Red
- 360 - normal split color sheme.
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I suspect it depends on the normal color of the given parts, where the cycle starts, after that, higher colors means going right at the color gradient, as it can be seen in the post-window of the form, just turned into a cycle.