jewel
瑜 centers on a precious gem or jewel, often implying a beautiful, flawless stone.
瑜 combines 王 (jade, jewel) with 俞, which likely contributes the sound. The character is used for fine jade or gemstones.
The left side 王 (jade) tells you this is a precious stone. The right side 俞 looks like a decorative carving on the jewel.
For ユ, imagine you holding a flawless jewel: you -> ユ, and the gem is so beautiful you can't look away.
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