KanjiJLPT N2
Ball

jewel, ball

Mnemonic

The king owns an exquisite ball — a polished jade gem so perfect it mesmerizes all who see it. He places a single drop of sacred oil on its surface, and the ball erupts with radiant brilliance. That tiny drop is the finishing touch that transforms a plain stone into the king's most treasured jewel.
Additional thoughts
Picture the King radical (王) as the gem's body, and the Drop (丶) as a glistening droplet of oil sitting on top, completing the kanji 玉. Without the drop, it's just a king; with it, it becomes something precious.
Quick recall
A king's jade ball needs one drop of oil to shine with perfection.

Details

The keyword for 玉 is ball. This kanji refers to a round, precious object such as a jewel, gem, or sphere. In ancient times, it was closely associated with beautiful polished stones and jade, which were highly valued in East Asian cultures. By extension, it can also convey the sense of something precious, refined, or perfect, much like a flawless gemstone.
On'yomi
ぎょく
Kun'yomi
たま、たま-、-だま