The coins issued by Bar Kochba marked the last coins issued by an autonomous Jewish State until the establishment of Israel in 1948. However, many of the Second Revolt coins had a second life! A number of Second Revolt silver denarii have been discovered with holes drilled through them, but these perforations never obliterated the meaningful designs.
Perforated Denarius (Herbst 1304)
Perforated Denarius (Mesh2, p.164, right)
These coins were discussed in the Mishnah (written before 200 CE): “A denarius which was invalidated and fashioned for hanging around the neck of a young girl is susceptible to uncleanliness” (Kelim 12, 7). And again, there is a reference in the Jerusalem Talmud: “With regard to a coin which was invalidated ... the second tithe is not exchanged for a coin issued by one who rebelled, such as Ben Kosiva (Bar Koseva)” (Ma’aser Sheni 1, 2).
Thus, it can be concluded that after the beautiful denarii of Bar Kochba became worthless as money, people chose to wear them as jewelry, proudly and defiantly displaying the symbols associated with the destroyed Temple of Jerusalem.
Sources: The Handbook of Biblical Numismatics