This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
硪 combines 石 (stone) with 我, but the exact historical development is uncertain. It may have originally referred to a type of stone or rock, but no clear meaning survives in modern Japanese.
The left side is stone 石, and the right side is 我 (oneself). Picture a stone that looks like a self-portrait, but its meaning remains a mystery.
For ギ, imagine a geeky geologist examining the mysterious stone: geek -> ギ, and the stone 硪 is their puzzling find.