On the breastplate of the High Priest, were affixed twelve gemstones (Shemot 28:17-20). There is almost no mention of most of them anywhere else in the Bible, aside from the parallel passage in Shemot 39:10-13. (A portion are mentioned in Yechezkel 28:13).
Because of the infrequent occurrences in the Tanach, along with the gap between current scientific precision and biblical nomenclature, it is difficult to identify with certainty the gems that appear in these verses. That said, let's take a look at one of them, the third stone - the bareket ברקת (mentioned in Shemot 28:17).
I have found many different translations for this stone, including:
agate, beryl, carbuncle, citrine, emerald, hyacinth, malachite, peridot, pyrite, rock-crystal, smaragd, topaz
And then some take either the easy way out or the more precise method (depending on your point of view), and translate it as "bareketh."
The etymology of bareket isn't much help. It likely derives from the word barak ברק - "lightning", and so means "flashing" or "sparkling" stone. Since gems are almost by definition shiny, all of the stones mentioned above could fit that description.
The attempts to identify the bareket with a gemstone that we know today is based on seeing its translation in ancient translations, as well as explanations offered by midrashim and later commentaries. I won't go into all of the analysis here (to see a good summary of traditional Jewish sources, see the Living Torah commentary on the verse here).
I'd like to take a look at how the word bareket ended up in European languages, and perhaps that will help us identify the stone.
Now, this is different from some words that entered European languages because they were borrowed as part of the Bible itself entering Europe (as I recently wrote about the words myrrh, aloe and cassia on the 929 site.) Rather, the name of the stone itself migrated into other languages.
From Hebrew (or some other cognate Semitic language, like the Akkadian barraqtu), bareket entered into Greek as smaragdos, which Latin borrowed as smaragdus, eventually becoming esmaraldus in Medieval Latin, esmeraude in French, and then "emerald" in English.
This might seem like a strange journey, particularly from bareket to smaragdos. But as this Philologos column explains (along with many other interesting linguistic details about the words we've discussed here and more) it's reasonable when you look at how certain letters are exchanged in phonetic shifts.
Philologos actually promotes a different theory than what I've presented here. He says that the Hebrew baraket may have its origin in a Sanskrit word - marakata:
Bareket strikes one at first glance as being an original Hebrew word that derives, quite appropriately for a gemstone, from the verb barak, to shine or sparkle. In Akkadian, the Semitic language of ancient Babylonia, we have the cognate noun barraktu, also meaning an emerald, and a similar verb. Perhaps indeed it was the influence of this verb that helped change an initial “m” into a “b” (a common shift in language, “m” being in essence a nasalized “b”), because scholars have known for a long time that the Akkadian word was borrowed from the Sanskrit marakata, an “emerald” or gem of green corundum. To this day, the marakata is one of the seven sacred stones of Hinduism, associated with the planet Mercury and the day Tuesday, on which it is traditionally worn.
Marakata is not only the ultimate source of Hebrew bareket. It is also that of Greek smaragdos, with which, except for the Greek’s initial “s,” it shares the same root consonants. (“Like “m” and “b,” “k” and hard “g,” and “t” and “d,” are similar sounds that frequently replace each other in speech.)
Most of the sources I looked at, including Klein and the Online Etymology Dictionary say the Sanskrit word was borrowed from a Semitic source. (For further discussion see this page). Whichever direction the word ultimately traveled (the Ben Yehuda dictionary mentions both theories, although sides with a Semitic origin), the b/m, k/g and t/d replacements still work here. As far as the prosthetic "s" at the beginning of smaragdos - I'm not sure. But since all explanations have Greek borrowing from a foreign language, for some reason the Greeks found a reason to add the "s".
So we do seem to have a linguistic connection drawn between bareket and "emerald." I don't think that's proof that the emerald as we define it today was on the High Priest's breastplate, but it's certainly possible that the ancient Greek smaragdos was similar to the stone mentioned in the Torah.