From the Maker:
Absinthe bistro saucers served a dual purpose in the pre-ban absinthe era. Besides serving as a coaster, they also functioned to indicate the price of absinthe being served. The price printed onto the bottom or side of the saucer corresponded with a color painted on the outside rim. This colored rim was used to tell the waiter how much to charge the customer by reading the different saucer colors when stacked. For instance, if three dark blue rimmed saucers (as shown above) were stacked, the waiter would know to charge the customer 9 French francs. When paying the bill, the money was generally left inside the coaster.
This saucer features a blue hand-painted rim with dark blue and silver accented pinwheel lines. The franc mark is printed into the bottom of the saucer.