Analysis of the electrum composition in ancient Greek coinage dating from 600 BC showed that the gold composition was 55.5% in archaic Phocaea. In the early classical period, the gold composition of electrum ranged from 46% in Phokaia to 43% in Mytilene. In later coinage from these areas, dating to 326 BC, the gold composition averaged 40% to 41%.
Electrum was often referred to as white gold in ancient times but could be more accurately described as "pale gold". The modern use of the term white gold usually concerns gold, silver and palladium alloys.
Electrum is possibly referred to three times in the Bible (i.e. if the Septuagint's translation of the uncertain term חַשְׁמַל is accurate). In all three instances it is used to describe a type of glow seen by the prophet Ezekiel in visions (Ezekiel Ch.1 Vs.4 and 27;Ch. 8 Vs. 2)
Electrum was much better for coinage than gold, mostly because it was harder and more durable, but also because techniques for refining gold were not widespread at the time. The discrepancy between gold content of electrum from modern Western Anatolia (70-90%) and ancient Lydian coinage (45-55%) suggests that the Lydians had already solved the refining technology for silver and were adding refined silver to the local native electrum some decades before introducing the pure silver coins cited below.
In Lydia, electrum was minted into 4.76-gram coins, each valued at 1/3 stater (meaning "standard"). Three of these coins (with a weight of about 14.1 grams) totaled one stater, about one month's pay for a soldier. To complement the stater, fractions were made: the trite (third), the hekte (sixth), and so forth, including 1/24 of a stater, and even down to 1/48th and 1/96th of a stater. The 1/96 stater was only about 0.14 to 0.15 grams. Larger denominations, such as a one stater coin, were minted as well.
Because of the variety of electrum's composition, it was rather difficult to determine the exact worth of each coin. Widespread trading was somewhat hampered by this, as a foreign merchant would offer rather poor rates on local electrum coin.
These difficulties were eliminated in 570 BC when pure silver coins were introduced. However, electrum currency remained fairly popular until approximately 350 BC. The simplest reasoning for this would be that, because of the gold content, one 14.1 gram stater would be worth as much as ten 14.1 gram silver pieces.
In 2002, Gibraltar issued commemorative coins which carried name Electrum and were made of alloy containing equal amounts of fine gold and fine silver, thus being electrum or 12 karat gold.