[iopq]

Both come from the Chinese term 青 which in modern Chinese would by itself refer to colors anywhere between sky blue and grassy green

青天 - clear skies

青草 - green grass

清葡萄 - 청포도 - white grape

[thaumasiotes]

As vague as 青 might be, I'd have to allow that it's a more accurate description of the color of a grape than "white" is.