rock, beach, shore
礒 centers on a rocky shoreline: a rock, a beach, or a shore where stone meets water.
礒 combines 石 (stone) with 義, which likely contributes the sound and may relate to a rocky or steep idea. The exact historical development is uncertain.
The left side is a stone 石, and the right side 義 looks like a complex rocky shape. Picture a stony beach where rocks pile up along the shore.
For ギ, imagine a rocky beach where you need a key to unlock a hidden cove: key -> ギ, and the stone shore guards the entrance.