The Byzantine Empire
The Byzantine Empire (Basileia to-n Romaio-n) is the term conventionally used since the 19th century to describe the Greek-speaking Roman Empire of the Middle Ages, centered around its capital of Constantinople. In certain specific contexts, usually referring to the time before the fall of the Western Roman Empire, it is also often referred to as the Eastern Roman Empire. To its inhabitants, the Empire was simply the Roman Empire and its emperors continued the unbroken succession of Roman emperors. During much of its history it was known to many of its Western contemporaries as The Empire of the Greeks due to the increasing dominance of its Greek population and distinct culture.
There is no consensus on the exact point when the Byzantine period began. Some place it during the reign of Emperor Diocletian, (284–305) who introduced administrative reforms that divided the empire into a pars Orientis (eastern half) and a pars Occidentis (western half). Some consider Constantine I the first Byzantine emperor. Others start it during the reign of Theodosius I (379–395) and Christendom's victory over pagan Roman religion, or, following his death in 395, with the permanent division of the empire into western and eastern halves. Others place it yet further in 476, when the last western emperor, Romulus Augustus, was forced to abdicate, thus leaving sole imperial authority to the emperor in the Greek East. Others again point to the reorganisation of the empire in the time of Heraclius (ca. 620) when Greek was made the official language and the Empire's conflicts turned largely to the east.[1] In any case, the changeover was gradual and by 330, when Constantine inaugurated his new capital, the process of further Hellenization and increasing Christianization was already under way.

Byzantine Gold Coins
Coming soon - 29th Nov 2006
The denomination of Byzantine gold coins followed on from those of the late Roman Empire, before evolving. They include:

• solidus
• nomisma
• semissis

CONOB
The abbreviation CONOB can be found usually in the exergue on the reverse of many gold coins of Byzantium.
CONOB. Constantinopoli obryzum. The solidus weighed 1/72 of the Roman pound. "OB" was both an abbreviation for the word obryzum, which means refined or pure gold, and is the Greek numeral 72. Thus the exergue CONOB coin may be read "Constantinople, 1/72 pound pure gold." -- "Byzantine Coinage" by Philip Grierson

Specifications

Coin	Diameter	Alloy	Weight	Description
Solidus	22.5 - 23.5	Gold	4.45	Numerous
Tremissis	16.5 - 17.5	Gold	1.55	Radiate Head

Notes
Diameter = millimetres
Weight = Grams

• Tremissis of Maurice Tiberius, 582 - 602 AD
  
• Histamenon Nomisma of Romanus III Argyrus