The heavily jeweled Imperial loros or pallium, derived from the version of the Roman toga worn by Consuls, was worn by the Emperor and Empress as a quasi-ecclesiastical garment. It was also worn by the twelve most important officials and the imperial bodyguard, and hence by Archangels in icons, who were seen as divine bodyguards. In fact, it was only normally worn on Easter Sunday, but it was very commonly used for depictions in art.

The men 's version of the loros was a long strip, dropping down straight in front to below the waist, and with the portion behind pulled round to the front and hung gracefully over the left arm. The female loros was similar at the front end, but the back end was wider and tucked under a belt after pulling through to the front again. Apart from jewels and embroidery, small enameled plaques were sewn into the clothes; the dress of Manuel I Comnenus was described as being like a meadow covered with flowers. Generally sleeves were closely fitted to the arm and the outer gown comes to the ankles (although often called a scaramangion), and is also rather closely fitted.

Emperor and Empress in full regalia, both with the loros,
Nicephorus III and Maria of Alania. 1074-81

Variations in the components of the loros are sometimes used to identify coin types or variations of coin types. These variations probably were not random, and may have been mint control marks or even "secret" marks used to authenticate genuine coins and detect counterfeits.

Source: http://en.wikipedia.org/wiki/Byzantine_dress