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The semissis (lit. 'half') was a fractional coin of the solidus and was worth more than the tremissis, a close 'cousin' equal to a quarter of a solidus. The semissis is a very obscure and puzzling gold coin issued during the height of the Roman Empire proper and the flourishing of the Byzantine Empire. Some sources suggest that the semissis might have originally been referred to as the semis – once a cast coin that was used during the early periods of the Roman Republic.  The value of a semis was originally half of an as, a fractional bronze Roman coin that was produced in large quantities for everyday transactions. Initially made from cast iron, a process that was very common for coins during the early days of the Roman Republic, it soon became a stuck coin, and the iron was then replaced with a far more malleable and lasting metal – bronze. Early examples of cast semis how that 'conservative iconography' of the early Roman Republic, featuring only mythological figures or deities instead of political figures and propaganda – a feature which would remain until its change into the struck semis that was commonplace only prior to the Second Punic War (218 – 204 BC). 
By the time of the Roman Empire, the issue of semis had begun to decline somewhat, so that by the time Hadrian began to reign, it had altogether disappeared from the then circulating types of Roman currency. How the semis became the gold semissis is still largely obscure – but some historians attest that the origin of the semissis was largely owed to the currency change that was opted and conducted by Constantine I in about 312 AD with the reintroduction of the solidus and its adoption as the sole official Roman gold currency replacing the aureus.  With the need for fractional currency that can be used in smaller transactions, and with the standard of the Byzantine Empire's coinage being set at the gold aureus, the development of smaller denominations such as the tremissis and the semissis were in order.
From a defunct bronze coin, the semis was now recreated into the gold coin known as the semissis, with many examples of the coin existing during the height of the Byzantine Empire, alongside its close relative the tremissis. Many examples of semisa exist, and unlike its more obscure origin the semis, the semissis was a very common coin used within the borders of Byzantium, and in some cases, even without – as its purpose was to hasten trade by allowing smaller denominations of equally valuable metal to that of the solidus to be used for general commerce. The use of semissis continued to flourish until the change of the solidus into the histamenon through the introduction of a lesser gold coin – the tetarteron. Until the latter days of the Byzantine Empire, when the standard of gold currency began to dwindle due to inevitable debasement, the production of semissis continued alongside the production of tremissis as well as a new type of currency to replace the histamenon introduced by the Emperor Alexios I Komnenos – the hyperpyron. During this currency change, semissi and tremissa began to debase dramatically, until the semissis was reduced to no more than a bronze coin (equal to its origin the semis) by the time gold coinage was abolished in Byzantium. 
Gold Semissis - References:
Content researched and created by Alexander Leonhart for coinandbullionpages.com © coinandbullionpages.com 2012
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