the jewel in someone's/something's crown
the jewel in (someone's or something's) crown
An asset, possession, or accomplishment prized as being the best thing someone or something possesses or has done. I have a lot of gorgeous cars, but this vintage 1965 Corvette Stingray is the jewel in my crown. The works of Shakespeare are the jewels in the crown of English drama.
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.
the jewel in someone's/something's crownor
the jewel in the crown of someone/something
COMMON If something or someone is the jewel in someone's or something's crown or the jewel in the crown of someone or something, it is the best thing they have, or their greatest achievement. He has written a number of excellent books but this novel is surely the jewel in his crown. The jewel in the architectural crown of North Yorkshire is almost certainly Castle Howard. Note: This expression was known in Victorian times, but is probably most well known as the title of a novel by Paul Scott, published in 1966, that formed part of a series set in the Raj, or Victorian India. In this title, India is seen as the `jewel', and the `crown' is the British Empire.
Collins COBUILD Idioms Dictionary, 3rd ed. © HarperCollins Publishers 2012