They haven't been cleaned or tampered with in any manner. The set (which includes the serial number for each plaque) is as follows.
I have provided several photos to give you a fairly good idea as to what's being offered and the overall quality and condition of the set. This is a rare opportunity to own a complete set of these handsome, hard to find plaques. For additional information on the plaques and their brief history, google'Sahara baccarat plaques'. The item "Complete set 5 1974 Sahara Casino Baccarat $1000 $500 Plaques Las Vegas chips" is in sale since Tuesday, January 19, 2021.
This item is in the category "Collectibles\Casino\Chips\Poker Chips". The seller is "listmonkey" and is located in Sierra Madre, California. This item can be shipped to United States, Canada, United Kingdom, Finland, Australia, Japan, China, Sweden, France, Hong Kong, Netherlands, Germany, Austria, New Zealand, Switzerland.