Reverse – The Cross and the Octagon
The cross on the reverse on most western medieval coins is double-lined or cross-patty (arms narrower at the center), see below:
Although there are examples of crosses with proportional arms and without double lines on medieval coins and the Curmsun Disc itself:
The presence of an octagon on the Curmsun Disc is exceptional as the it is mostly seen in the medieval architecture and jewelry and never on medieval coins or medallions.
The center of Aachen Cathedral (Palatine Chapel) has the shape of an octagon and the coronation of the Ottonians took place there between 936-1531 (link). Number eight – ocatgon – can be found over and over again in the Palatine Chapel (link).
The great dome above the altar is octagonal because Charlemagne placed special significance on the specific number eight. Number eight appears frequently in the Holy Bible, it was charged with symbolism in the Christian world during medieval times. An octagon can be made by drawing two intersecting squares within a circle. The circle represents God’s eternity while the square represents the secular world. The four corners also represent the four directions to heaven and the four characteristics of man. Charlemagne saw the number eight as symbolizing the power of the Franks and the Roman Empire, the ruler of both the secular and religious worlds. The Franks were later to become known as the Holy Roman Empire. The Emperor’s throne built in the 10th century overlooks the altar. The two relics in his hands were symbols of his power as ruler of two worlds. Charlemagne is holding a sceptre symbolizing his rule of the secular world in his right hand, while in his left he holds an orb, the symbol of the religious world. (link)
The baptismal font in Cologne baptistery also has the shape of an octagon. The large, sixth-century octagonal basin complete with drain (right) was discovered to the east of the cathedral in 1866 and is protected to this day by a brick vault constructed by the cathedral’s head architect, Richard Voigtel. The basin was used for the Christian rite of baptism and bears all the hallmarks of such a sixth-century structure (e.g. the accentuated areas at the corners for the supports of a ciborium). It was built on top of the walls of a Roman house that already contained an octagonal basin (link).
Baptismal font, Cologne baptistery
Photo: © Dombauarchiv Köln, S Ristow
Similarities with another artifact
Another object that got some things in common with Curmsun Disc is the Imperial Crown of the Holy Roman Empire, see image below.
The crown is octagonal instead of circular which is most common for royal crowns. The Latin cross on the crown reminds of the cross on the Curmsun Disc and the unidentified cross in Cologne. The gold content in the crown is unusually high (22-charat) which also pleads in exact amount for Curmsun Disc, see section “Authenticity”. It is unknown if the Imperial Crown of the Holy Roman Empire is manufactured during Otto I, Conrad II or Conrad III.
The imperial crown of the Holy Roman Empire
Photo: User:Bede735c, Wikipedia