beautiful black jewel, nine
玖 centers on a beautiful black jewel, and is also used as a formal or financial numeral for nine.
玖 combines 王 (jade/jewel) with 久, which likely contributes the sound. The character originally referred to a black jade-like stone, and later was borrowed as a formal numeral for nine.
The left side 王 is a jewel, and the right side 久 looks like a person bending over a dark stone. Picture a beautiful black jewel being polished until it shines.
For キュウ, imagine a beautiful black jewel shaped like the number nine (9), and you say 'cue' when you see it: cue -> キュウ, and the jewel is a nine.
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