clear
瑩 centers on clarity and transparency, like a polished gem or a bright light that makes things clear and visible.
瑩 combines 玉 (jade/gem) with an upper element that likely represents bright light or fire, suggesting a gem that shines clearly. The exact historical development of the upper component is uncertain.
The bottom 玉 is a gem, and the upper part looks like bright flames under a cover. Imagine a polished gem glowing with inner fire, making everything around it clear and bright.
For エイ, picture a clear, bright gem shaped like the letter 'A' (エイ) shining on a pedestal: 'A' -> エイ, and the gem's clarity is unmistakable.