A precious stone, like a large ruby or garnet, of a dark, deep red color, said to glitter even in the dark, and to sparkle more than the ruby. The word is put to represent two different Hebrew words, one of which, Ex 28:17; Eze 28:13, is commonly thought to mean the emerald; and the other, Isa 54:12, may mean a brilliant species of ruby.
(Ex 28:17; 39:10; Eze 28:13). Heb. barkath; LXX. smaragdos; Vulgate, smaragdus; Revised Version, marg., "emerald." The Hebrew word is from a root meaning "to glitter," "lighten," "flash." When held up to the sun, this gem shines like a burning coal, a dark-red glowing coal, and hence is called "carbunculus", i.e., a little coal. It was one of the jewels in the first row of the high priest's breastplate. It has been conjectured by some that the garnet is meant. In Isa 54:12 the Hebrew word is 'ekdah, used in the prophetic description of the glory and beauty of the mansions above. Next to the diamond it is the hardest and most costly of all precious stones.
(in English "a little coal," "a bright red gem"): eqedach, boreqeth, the former in Isa 54:12 from qadach "to burn," the latter from baraq "to flash." A brightly flashing stone. A smaragd (Septuagint) or corundum, of green glass color, transparent, and doubly refractive; the emerald (Ex 28:17); third stone in the first row m the high priest's breast-plate (Eze 28:13).
Two Hebrew words are so translated.
1. eqdach, a stone of a fiery sparkling nature. Isa 54:12.
This word represents two Hebrew words. The first may he a general term to denote any bright,sparkling gem,
is supposed to be and smaragdus or emerald.
CARBUNCLE ????, Ex 28:17; 39:10; Eze 28:13; and ??????, Ecclesiastes 32:5; Tobit 13:17; a very elegant and rare gem, known to the ancients by the name ??????, or coal, because, when held up before the sun, it appears like a piece of bright burning charcoal: the name carbunculus has the same meaning. It was the third stone in the first row of the pectoral; and is mentioned among the glorious stones of which the new Jerusalem is figuratively said to be built. Bishop Lowth observes that the precious stones, mentioned Isa 54:11-12, and Re 21:18, seem to be general images to express beauty, magnificence, purity, strength, and solidity, agreeably to the ideas of the eastern nations; and to have never been intended to be strictly scrutinized, and minutely and particularly explained, as if they had some precise moral or spiritual meaning. Tobit, in his prophecy of the final restoration of Israel, Tobit 12:16, 17, describes the new Jerusalem in the same oriental manner.