This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
The exact historical development of 玪 is uncertain. It visually combines 王 (jade) and 今, but the original meaning and component function are unclear.
The left side 王 suggests jade or a precious stone, and the right side 今 looks like a cover or a person. Without a clear meaning, picture a mysterious jade artifact with a lid marked 今.
For カン, imagine a can made of jade: can -> カン, and the jade 王 side makes it precious.