An ink color sample page from a Japanese sample catalog of matchbox cover designs, most likely from the 1960s. This very scarce catalog is currently available from the Boston Book Company.
Gem color chart which appears to be partially hand stenciled. From Vintage Printables.
Lichen color charts from the Svensk Lafvarnas Farghistoria by Johan Peter Westring. Printed in 1805-09. Via the Biodiversity Heritage Library archive.
A 1944 color chart from The Technique of Colour Printing by Lithography: A Concise Manual of Drawn Lithography by Thomas E. Griffits, Faber and Faber. From the Crossett Library Flickrstream.
A 1942 Color Harmony Manual by Egbert Jacobson Color Laboratories Division, Container Corporation of America. From the Crossett Library Flickrstream.
The toast gradient scale from Things Organized Neatly.