In the 18th century we see that the Pugs more and more resemble the Pug of early 1900 which is the sort of Pug the Retro Pug breeders work to breed. Notice though, that during this century the Pug still had colors that were later non-recognized. Furthermore, most Pugs of the 18th century had cropped ears which can be seen below.
Below, a brindle pug with cropped ears. Some sources on the internet say that the painter is Leonard Knyff (1650-1722) and that it was painted in 1702. Others say that it was painted by Jean-Baptiste Oudry (1686-1755) in 1730.

Notice that the Pug below is piebald and with cropped ears. It also does not have the curled tail.

Jean-Baptiste Oudry (1686-1755)
Notice the black-and-tan color of the Pug below, as well as the cropped ears.

Renée Willes writes in the book Allt om mops, (2006) that the Pugs below belonged to king Fredrik I and queen Ulrika Eleonora. Note that one of the Pugs seems to be white and both have cropped ears.

David Kock (1675-1744)
Notice that the Pug below has the fawn color that will be the recognized color of the Pug in the British Kennel Club (founded 1873). Also notice the cropped ears. Renée Willes writes in her book Allt om mops (2006: 76) that the Pug belonged to king Fredrik I.

Painter unknown

William Hogarth (1697-1764)
Notice the black color of the Pug below. This color was not recognized by Hugh Dalziel who set the standard of the Pug in the 1880s.

Notice the russet color and white marks of the Pug belwo as well as the cropped ears.

Christophe Huet II (1700-1759)
Is Arnold Rosenhagen’s Pug below white or has it become white with age?

Notice that this Pug is piebald and with cropped ears:

Thomas Gainsborough (1727-1788)
As is seen, the Pug below is a variant that was later preferred as the Pug. Notice the cropped ears and the bells around the neck that was commonly seen on Pugs in the 19th century.
