Easton's Bible Dictionary (1897)
The rendering in the Authorized Version of the Hebrew word tarshish, a precious stone; probably so called as being brought from Tarshish. V. , “chalcedony;” 39:13). , “stone of Tarshish”). It is mentioned in Cant. 5:14; Dan. 10:6; Rev. 21:20. In Ezek. 28:13 the LXX. render the word by “chrysolite,” which the Jewish historian Josephus regards as its proper translation. This also is the rendering given in the Authorized Version in the margin. That was a gold-coloured gem, the topaz of ancient authors.
Smith's Bible Dictionary (1863)
(tarshish) occurs in (Exodus 28:20) It is generally supposed that the tarshish derives its name from the place so called, in Spain. Beryl is a mineral of great hardness, and, when transparent, of much beauty. By tarshish the modern yellow topaz is probably intended, while in (Revelation 21:20) a different stone is perhaps referred to, probably the mineral now called beryl, which is identical with the emerald except in color, being a light green or bluish-green.
Hastings' Dictionary of the Bible (1898) & Schaff's Bible Dictionary
BER'YL . Ex. 28:20. By the Hebrew word "tarshish " modern yellow topaz is supposed to be meant. This designation seems to indicate the place from which it was brought. Beryl, in the N. , Rev 21:20, is probably a different stone, and very likely the mineral now so called, which is found in Palestine, but was less abundant and more precious in ancient times than in modern. It is usually of a light-green color and considerably opaque.