This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
璑 combines 王 (jade) with 無, which likely contributes the sound. The exact historical development is uncertain.
The left side 王 suggests jade or a precious stone, but the overall meaning is unclear. Imagine a mysterious uncut gem with no known name.
For ブ, picture a boo sound of disappointment when you cannot identify the stone: boo -> ブ.