“Alvar was so disgustingly smug about earning one that he told my mom she should keep it on the mantel in our main sitting room...”
A Radiant is the highest honor that Foxfire prodigies receive after they complete the basic levels. Alvar received this award pre-Keeper. It is described as a fist-sized crystal prism that is heavy like a paperweight, and when held up to the light, flashes rainbow sparkles, illuminating the Foxfire seal and the name of the recipient at its base. When he brought it home, he told Della to put it on the mantel so it could "inspire Fitz and Biana to work harder." In Book 6: Nightfall, Fitz gives it to Sophie as a present so she can hurl it down the extremely steep stairs to Brumevale and shatter it as revenge for all that Alvar did. Sophie offered to let Fitz, Biana, and/or Dex throw it, but they all agreed to let Sophie be the one to destroy it because Alvar had hurt her the most. She threw it extra hard for them with the help of the Sucker Punch that Dex made for her because he wanted to assist in the breaking due to his kidnapping during Book 1: Keeper fo the Lost Cities by Alvar and the rest of the Neverseen.