灰 ash/ gray

The cliff burned up - all that remained was gray ash.

gray color ★★☆☆☆ KUN ON
灰 (ash/ gray) + 色 (color) = 灰色 (gray color)

ashtray ★☆☆☆☆ KUNKUN
灰 (ash/ gray) + 皿 (plate) = 灰皿 (ashtray)