|Coins from Kingdom of Jerusalem in British Museum|
(l. to r.) dinar (1162-75), Arabic bezant (1140-80),
Christian bezant (1250-) [source]
Discussions of items of currency in history break down into two parts: "Where did it come from?" and "What is it worth?" The first part is far easier to deal with. You might guess that the name bezant comes from its relationship to its place of origin: Byzantium.* Gold coins could be called after a particular place because they were not that common: few places minted them, silver and bronze being the more common metals used (hence, of course, the traditional use of gold, silver, and bronze for medals in competition). Gold coins were used for special occasions or for attention-getting: gifts, tributes, awards or, as we saw yesterday, impressing your fiancé's guardian.
Gold coinage started in antiquity in the Middle East and eastern Mediterranean and slowly spread westward as trade increased. Of European merchants, those from Italy had the most familiarity with eastern gold coins from the east and used the term bezant to refer to gold coins from Egypt (the dinar in the above picture); Marco Polo used bezant to refer to the gold coins he saw in East Asia.
What was a bezant worth? That depended on a lot of factors, and there was no "gold market" like we have today that monitors fluctuations in price. The best we have in most cases is a comparison to other coins. Marco Polo describes one bezant as worth 20 groats or 133.33 tornesel. This tells us only that gold coins were proportionally far more valuable than other metals. The gold coins that were minted in England in the 10th and 11th centuries were decreed to be worth nine times the value of a similar-sized silver coin. Suffice it to say that any gold coin had much more purchasing power than most coins in circulation that the average person would be likely to use on a daily basis. Unfortunately, we do not have lists of prices of everyday items or services from history...but we do have some, which we will look at tomorrow.
*Byzantium was re-named Constantinople in 330CE; later, of course, it became Istanbul in 1930. Enjoy the song.