A precursor to the modern suit waistcoat. From this page:
What is today recognized as a man’s three-piece suit began to develop in the late 17th century and was well established by the 18th century. In the early 17th century most men wore as the outer layer of garments a tailored doublet and full breeches. In the middle of that century the vest was introduced to European fashion from Asia Minor. Looser forms of doublets left unbuttoned allowed the long vest to be seen beneath.
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Mary K • Link
Anyone who is able to watch BBC 4 at 20.30h this evening (3rd January 2018) could see a team of tailors, guided by fashion historian Amber Butchart, re-creating a suit of clothes typical of one worn by Charles II.
San Diego Sarah • Link
There was some leeway in the design of the Persian vest introduced by Charles II in 1666.
Pepys' friend, Admiral Sir John Harman, was a handsome 41 year old in 1666. He wears the long coat version in his "Flagmen of Lowestoft" portrait. It is heavily barred with gold and silver braiding and Harman wears a loosely knotted linen cravat with a heavy leather sword belt.
Pepys saw this painting, either begun or finished, in Peter Lely's studio on 18 April, 1666:
https://en.wikipedia.org/wiki/Joh…
(You can see more of the vest on Wikipedia than on the Greenwich museum site)