Some background and trivia on the paintings "The Blue Boy" and "Pinkie". Both of these paintings were painted with oil on canvas, and are full length portraits painted in the 18th century. However, this is where the similarities end.
"The Blue Boy" was painted by Thomas Gainsborough in 1770. The boy in the painting was not a royal, as some guess, but actually a boy named Jonathan Buttall. He was the son of a hardware merchant who was friends with Gainsborough. X-rays of this painting show that the canvas had other work behind the current painting we know today. There was found an unfinished painting of an older man before Gainsborough used the canvas to paint "The Blue Boy". Also found was a dog painted next to the boy, which Gainsborough covered up with a pile of rocks. The style worn in the painting was in homage to Sir Anthony Van Dyck, and is from the early 17th century.
"Pinkie" was painted by Thomas Lawrence in 1794. The girl in the painting is Sarah Barrett Moulton. In her family, her nickname was "Pinkie" or "Pinkey". She was just 11 years old when the painting was made. It was by her Grandmother's request that the painting was commissioned. Unfortunately, Sarah died a year later at the age of 12. It is not known what the cause of her death was, but perhaps it was related to a cough she was recovering from that her grandmother mentioned in a letter a few months before.
The two paintings are now on display at The Huntington Library and Gardens. Henry Huntington bought the paintings in the 1920's. "Pinkie" was one of the last purchases made by Henry Huntington before his death. The paintings were not associated with each other until Huntington had purchased them. They were painted 24 years apart, by different artists, and the style of dress shown in the paintings are about 150 years apart!