A rare Byzantine gold coin dating back to the 11th century has been found in the ancient city of Perperikon, the renowned Bulgarian archaeologist Nikolay Ovcharov revealed on Sunday.

The coin made of 23-carat gold is depicting Byzantine Emperor Basil II (976–1025) and his younger brother Emperor Constantine VIII (1025-1028).

It is a touch lighter in weight than the standard 4.4-gramme tetarteron coins minted in the Byzantine Empire in the 10th and 11th century. Only two or three out of 100 tetarteron coins minted at the time were lighter than the standard ones, Ovcharov told a news conference in Sofia.

The coin is very vell preserved which indicates it has been used as investment gold, serving as collateral in business transactions rather than as a means of payment in everyday money circulation.

Ovcharov also said the archaeologists have found a lead stamp that belonged to a Byzantine nobleman active in the defence of the empire. Only two other stamps belonging to the same Byzantine aristocrat have been found until now and both of them are in private collections, Ovcharov said.

The announcement of the new discoveries comes about a week after Ovcharov revealed that Bulgarian archaeologists have unearthed in Perperikon, in southeastern Bulgaria, a peculiar close combat bladed weapon used by Thracian warriors.