Peeta's pearl



In Catching Fire, while diving for seafood to eat for dinner, Peeta Mellark finds a pearl in a oyster and gives it to Katniss Everdeen as a gift. When he found it, he told Finnick Odair that when enough pressure is placed on coal it will turn into pearls. This is an inside joke between him and Katniss referring to Effie Trinket's mistaken pronouncement which confused pearl creation with the creation of diamonds. The Hunger Games, Chapter 6</ref

In Katniss  puts Peeta's pearl to her lips and thinks it's like "A cool kiss from the giver himself".