Jak 3 skull gem locations Requirements Trophy type This page lists the locations of all 456 skull gems in Jak 3. A skull gem is a glowing yellow gem obtained from killing metal heads. Collecting skull gems is related to trophies titled "Oh My Head", "My Head Hurts", and "Head Over Here". Collecting 25, 125, and 250 skull gems unlocks a bronze, silver, and gold trophy, respectively.