Seymour, Dale. Antique Gambling Chips - Revised Edition, Page-15:

Paste-on chips were simply plain composition chips with a colored, lithogaphic sticker pasted on the chip. There was no indentation for the design adhesive and a shellac covering. Paste-on chips were first made in the mid-1800s and soon evolved to a "inlaid litho" chip. The inlaid litho chip differed from the paste-on in that a very thin recess was molded into the chip and the printed design was set in this recess in the face of the chip. It is often difficult to tell a "paste-on" chip from an "inlaid litho" chip without peeling or extracting the piece of paper from the chip.