Wikipedia lists the sett as [Y/6] R4 MB26 K32 G4 W4 Lv4 W4 [G/44]. Im not familiar with the [Color/Count] notation, the count appears to be doubled, possibly to indicate the total count of that thread in the mirror section.
Colorado house joint resolution 97-1016 makes this official but doesnt provide a thread count. It speaks of "cerulean blue" which I approximate with the unique (669) color.
I place this image in the public domain, in the hope that it will increase interest in tartans and tartan design.
Neale Pickett <neale@woozle.org>