Easton's Bible Dictionary (1897)
, “high-priced” or valuable things, or, as some suppose, “that which grows high,” like a tree (Job 28:18; Ezek. 27:16), according to the Rabbins, red coral, which was in use for ornaments. The coral is a cretaceous marine product, the deposit by minute polypous animals of calcareous matter in cells in which the animal lives. It is of numberless shapes as it grows, but usually is branched like a tree. Great coral reefs and coral islands abound in the Red Sea, whence probably the Hebrews derived their knowledge of it. It is found of different colours, white, black, and red.
The red, being esteemed the most precious, was used, as noticed above, for ornamental purposes.
Smith's Bible Dictionary (1863)
(Ezekiel 27:16) A production of the sea, formed by minute animals called zoophytes. It is their shell or house. It takes various forms, as of trees, shrubs, hemispheres. The principal colors are red and white. It was used for beads and ornaments. With regard to the estimation in which coral was held by the Jews and other Orientals, it must be remembered that coral varies in price with us. Pliny says that the Indians valued coral as the Romans valued pearls.
Hastings' Dictionary of the Bible (1898) & Schaff's Bible Dictionary
COR'AL, Eze 27:16, was an article of Tyrian merchandise, and is well known as a marine production, found in almost every variety of shape and size, and sometimes increasing to such an extent as to form the basis of islands, or to stretch out in dangerous reefs for many miles. It is capable of being worked up into beads and other ornaments; for which use the red species is the most valuable. Job mentions it in connection with pearls. Job 28:18.