These dyes, which are found only in standard Unidentified Dyes or in gem store Dye Packs are of exotic rarity and provide special patterns to the dye slot of your armor when applied. You then choose which colors to go with it through a seperate menu option when a pattern is applied.
Some basic examples:
Checkerboard/Chessboard Dye – a pattern of alternating squares
Diamonds – A diamond pattern.
Horizontal, Vertical, and Diagonal Stripes (found separately)
Star spangled.
Rainbow – Obviously doesn’t follow the “choose your colors” feature of other patterns.
And more.