ChristianAnswers.Net WebBible Encyclopedia
Two different words are found in Hebrew to denote coal, both occurring in Prov. 26:21, “As coal [Hebrew: peham; i.e., ‘black coal’] is to burning coal [Hebrew: gehalim].” The latter of these words is used in Job 41:21; Prov. 6:28; Isa. 44:19.
The words “live coal” in Isa. 6:6 are more correctly “glowing stone.”
In Lam. 4:8 the expression “blacker than a coal” is literally rendered in the margin of the Revised Version “darker than blackness.”
“Heaping coals of fire on the head” symbolizes overcoming evil with good. The words of Paul (Rom. 12:20) are equivalent to saying, “By charity and kindness thou shalt soften down his enmity as surely as heaping coals on the fire fuses the metal in the crucible.”