Relics that are claimed to be the Holy Nails with which Jesus was crucified are objects of veneration among some Christians, particularly Roman Catholics and the Eastern Orthodox. In Christian symbolism and art, they figure among the Arma Christi or Instruments of the Passion, the objects associated with the Passion of Jesus. Like the other Instruments, the Holy Nails have become an object of veneration among many Christians and have been pictured in paintings.
The authenticity of these relics is doubtful. The Catholic Encyclopedia wrote:[1]
Very little reliance can be placed upon the authenticity of the thirty or more holy nails which are still venerated, or which have been venerated until recent times, in such treasuries as that of Santa Croce in Rome, or those of Venice, Aachen, the Escurial, Nuremberg, Prague, etc. Probably the majority began by professing to be facsimiles which had touched or contained filings from some other nail whose claim was more ancient. Without conscious fraud on the part of anyone, it is very easy for imitations in this way to come in a very brief space of time to be reputed originals.
It is not clear whether Jesus was crucified with three or with four nails, and the question has been long debated.[1] The belief that three nails were used is called Triclavianism.