Ivlivs is a gold coin which belonged to Jason Grace until its destruction in The Lost Hero.
When flipped, it turns into a double-edged Imperial Gold sword when the coin comes up heads or a lance when the coin comes up tails. The sword side has an image of Julius Caesar, while the lance side has a double headed axe and the word IVLIVS. This could be a reference to the minted face of Julius Caesar in the coin. The axe is a reference to the Caesar's victory over Gaul, in a symbol of an axe. The coin is currently destroyed.
When the teens from the Wilderness School travel to the Grand Canyon, Jason begins nervously rubbing Ivlivs when he is around Dylan. When it is seen by Leo Valdez, he says, "Dang, is that gold? You been holding out on me!"
He first learns that it could turn into a lance when showing the other campers that he is a son of Zeus by calling down lightning. It was later destroyed by Enceladus when he fought Jason at Mount Diablo. It was later replaced by a gladius given to Jason by Juno (Hera). When Ivlivs turns into a javelin, it is seven feet long, made entirely of metal, with an extremely sharp tip. When it is a double edged sword it is 2 feet long, double-edged and probably one-handed with a ridged grip and it fits Jason's hand perfectly. When it is a coin, it is thick, slightly uneven, and about the size of a half-dollar.
- Iulius (IVLVIS) would actually be pronounced as "Yulius" because in the Roman alphabet, neither "U" nor "J" existed and is then replaced by "V" and "I" respectively, with the 'I' changing its form to a 'Y' sound in certain cases. One evidence is the name sign shown in government buildings where the U-V and J-I Roman alphabet rule is used.
- It somewhat resembles a Golden drachma, but it is actually an aureus.
- It was first revealed that IVLIVS was made of Imperial Gold by Medea when she showed them a forge that could melt Imperial Gold.
- It was destroyed at the end of The Lost Hero. When Jason tried to pierce the back bone of Enceladus, it was smashed by his foe's javelin and it exploded in a blast of white light. The blast released so much power it fused the sand and rock together, forming a glass pit that Enceladus falls into.
- The spelling Ivlivs appears to be somewhat of a misnomer; though the original Latin spelling would employ the usage of "V" in place of "U", according to the time of the weapon's origin, the Roman alphabet did not make use of lowercase letters; thus, the weapon's name would actually be read as IVLIVS.