Stamp paper can be found in just about every color but the differences lie in how those colors are achieved. Color dyes can be mixed in during the papermaking process, applied to the front or both sides or created by the ingredients of the paper rather than the use of dyes.
US Carrier 20L03 issued in 1875 on pink wove paper.

US Local 20L56 issued in 1882 on pink wove paper.

Switzerland #201 issued in 1924 on surface colored granite paper with silk fibres.

No color on back, but the odd markings of the granite paper are just visable under the dotted pattern that is evidence that this stamp had grilled gum. You can also see the Swiss Cross watermark.

In wm fluid.

US #357 issued in 1909 on bluish paper (certified) made from 35% rag stock instead of all wood pulp.
Image Insert:
The bluish color permeates throughout and effects the color of the ink......notice the bluegreen look of this stamp...not the solid green that is common on these Washington/Franklins.
