The Witches' Gloomix is a plot element in the second season, a parallel to the Winx Club's Charmix. It takes the form of a glowing necklace or wrist cuff with a single gem on the end. The Trix receive the Gloomix from Lord Darkar, and use it in a Convergence during the second half of the season. So far, the only witches to earn this are Icy, Darcy, and Stormy. Along with the Trix's Gloomix are and the other ones are a yellow zone and two green leg bracelets.
Gloomix is the witch version of Charmix, given to them by Lord Darkar.