Onyx Marshal's token was an exquisite silver locket containing an emerald gem embedded into the center. The locket was a surprise gift to Onyx given to her by her older brother, Mason. Mason had bought the locket himself, and had originally intended the gift for their mother on her birthday, but because of her death, Mason decided to give it to the "next special girl in his life", Onyx. While Onyx had expected a token, she had not foreseen something of this calibur, and was more than content with the gift.
Onyx wears the locket throughout her stay at the Capitol, and she is next seen again toying with the locket before the second of the training days. Onyx describes the luminosity of the gem, comparing it to "hope" and noticing the contrast of the shimmering gem to the abysmal black tablecloth. Later, Hyre assists Onyx with unclasping the necklace.
Onyx continues wearing the locket in the Games, even until her final breath. After Hyre has calmed himself after Onyx's death, he takes the liberty of removing her locket, wearing it for himself so he has something to remember her by. Later, as Hyre examines her locket, he discovers a switch on the side, allowing the locket to spring open. Inside, there is a small picture of Onyx's parents, as well as a small note intricately folded to fit inside. The note, however, is quickly blown away by the wind. As it unfolds, Hyre spots his name on the letter, revealing that the letter was directed toward him. Unfortunately, the note flies into the fire, burning to a crisp before Hyre can stop it. Hyre decides it is better not to know what exactly the note said. Later, Hyre looks at the locket once more. He sees Onyx's face within the gem and promptly drops the locket into his backpack--preferring not to be haunted by anymore ghosts.
Onyx viewed the locket as a symbol of hope, and discovered how to open the locket sometime in the Capitol, placing a hand-written note describing her true feelings for Hyre within.