Roy Precious - Antiques & Fine Art has dated this piece to the 17th Century.
Rare and important, this is a superb quality portrait, a free copy by van der Stock after Mijtens, based on a detail of the large portrait of the prince's father and family: Portrait of Frederick William, Great Elector of Brandenburg 1620–1688, with Luise Henriette of Orange and the Princes Karl Emil, Frederick etc. Painted c. 1664/67 by Jan Mytens (Johannes Mijtens).
In the inventories of one of Amalia's other daughters, Henriette Catharina, there are many assignments to Paulus van der Stock for copying the work of Mytens from 1664 onwards.

KARL (CHARLES) EMIL, Electoral Prince of Brandenburg (16 February 1655, Berlin – 7 December 1674, Strasbourg) was a German prince as heir-apparent to the Electorate of Brandenburg.
He was the second son of Frederick William, Elector of Brandenburg, and his first son to survive infancy - his elder brother William Henry had died at less than two years old in 1649. Born on his father's thirty-fifth birthday after six years of unsuccessful pregnancies for his mother Countess Luise Henriette of Nassau, he was much hoped-for and was raised to be like his father - spirited, quick-tempered and always in favour of war and the hunt (the most effective way of subduing him was always for his tutor to take away his sword for a few days).

In 1670 he was made colonel of the Regiment Radziwill zu Fuß and four years later he and his father headed the Brandenburg force on its incursion into Alsace during the Franco-Dutch War. The campaign soon became mired into incessant maneuvering with the imperial commander Bournonville afraid or unwilling to give battle. A cold wet autumn arrived, leading to supply and sanitary problems and disease in the Brandenburg army. Charles became ill late in November and at the start of December was sent to Strasbourg to recover. After seven days of a rising fever, he then died of dysentery at the age of 19.

Our thanks to Adam Busiakiewicz, art historian, for research, and to Sabine Craft-Giepmans MA, Head of Fine Arts until 1750 at the RKD - Netherlands Institute of Art History, for the identification of the artist and confirmation of the sitter.
SIZE: 43.5 x 38 inches inc. frame.
PROVENANCE: Many years in a Suffolk farmhouse, unframed and dirty, where identities of sitter and artist were forgotten.
Roy Precious - Antiques & Fine Art has dated this piece to the 17th Century.
Roy and nadine precious: specialists in portraiture from the 16th to the 20th century. Established in 1972.
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