Camp Necklace

The Camp Necklace is given to each Camp Half-Blood camper at the end of each summer at Camp Half-Blood. The cabin senior counselors vote on the biggest event of the summer and paint it on a bead.

The Lightning Thief
Features a black bead with a green trident. This was given to the campers on completing their summer at Camp Half-Blood. The bead represents a son of Poseidon going into the darkness of the Underworld, and making it out alive.

The Sea of Monsters
Features the Golden Fleece hanging from Thalia's pine tree. This was given to the campers upon completing their summer at Camp Half-Blood. The bead represents the most special event of that year, the retrieval of the Golden Fleece from Polyphemus' Island by the campers to save Thalia's pine tree from poisoning.

The Battle of the Labyrinth
Features an intricately designed maze to represent Daedalus' Labyrinth. This was given to the campers on completing their third summer at Camp Half-Blood. The bead represents the most special events of that year, the battle that took place in the Labyrinth and the events related to it.

The Last Olympian
Features the Empire State Building with the names of the campers who fell in the Battle of Manhattan in tiny Ancient Greek letters. This was given to the campers on completing their fourth summer at Camp Half-Blood. The bead represents the most memorable event of that year, the Battle of Manhattan against Kronos' army, the terrible casualties and honor to the loved ones lost.

The Lost Hero
It does not mention a bead being made because it was in the winter, during the same year of The Last Olympian.

The Son of Neptune
No bead was mentioned as this story focuses on the Roman campers at Camp Jupiter and they do not give beads, instead burn a new line on the tattoos on the arms of their campers.

The Mark of Athena
Most of the journey in the book was spent away from both camps as the Seven sail back to the Ancient Lands. This is also due to the fact that the book took place between June 25th and July 1st, but camp beads are only given out at the end of the summer session every year, usually in the middle of August.

Annabeth's Necklace
There are five beads on Annabeth Chase's necklace at the start of The Lightning Thief, from the years before Percy Jackson's arrival on Camp Half-Blood. The ones she mentioned were the beads featuring Thalia's pine tree for her first year at camp, a Centaur in a prom dress, and a Greek trireme on fire. Percy interrupts her, so the last two of her beads are unknown. Annabeth also has her father's college ring on her necklace. In The Mark of Athena, it is mentioned that Annabeth was given a red coral pendant by Percy to her when they started dating. Percy brought the coral for her from Poseidon's Palace.

Percy's Necklace
Percy has four beads total on his necklace, along with other items he has received at different times.

In The Last Olympian, Percy put his father's gift, a sand dollar, on his necklace and later gives it to the Hudson River and the East River. In The Son of Neptune, Percy put his Probatio tablet on his necklace. At one point in the book Percy loses his necklace to Queen Hylla, and later gets it back from Hazel Levesque.

Trivia

 * Interestingly, none of the official images of any campers see them wearing their camp necklaces.