I'm preparing for a visit to the American Sign Museum, and this is one of the exhibits I'm excited to see 'in the flesh'.
Gilding samples such as these were used to talk to customers about the many visual effects that can be achieved with the medium of gold leaf on glass. And, in this case, it is a set of 28 samples from a master of the craft: Raymond J. LeBlanc. His book, Gold Leaf Techniques (1973) remains the definitive text for anyone learning to gild.