There's a thread on it here:
http://www.xmarksthescot.com/forum/s...ighlight=green

Hamish said:
As everyone else has stated, black is the most acceptable. Coloured Prince Charlies should only be worn - no, CAN only be worn - with a tartan containing a complimentary colour. For example, a dark green PC would look ghastly with a Royal Stewart kilt, but would work well with a Modern Gunn or even Black Watch kilt. Unless you wear just one tartan, you are going to be very limited with a coloured PC.
I would think since tartans are not the same one color, the jackets don't have to be either- whereas proper tuxedo pants are always black. If there's no black in your kilt, it might look better with a green or maroon jacket anyway.