noun Date: 1649 the jewels (as crown and scepter) belonging to a sovereign's regalia, the most attractive or valuable one of a collection or group
CROWN JEWEL
Meaning of CROWN JEWEL in English
Merriam Webster. Explanatory English dictionary Merriam Webster. Толковый словарь английского языка Мерриам-Уэбстер. 2012