Crown jewel and Precious stone

Crown jewel noun - A precious stone that is a valuable part of a sovereign's regalia.

Precious stone and crown jewel are semantically related in gem topic. In some cases you can use "Precious stone" instead a noun phrase "Crown jewel".

Precious stone noun - A precious or semiprecious stone incorporated into a piece of jewelry.

Crown jewel and precious stone are semantically related in gem topic. Sometimes you can use "Crown jewel" instead a noun phrase "Precious stone".