Enchanted Mage's Gem is crafted with Magic Craft in Mabinogi. This page lists everything needed to make it, checked against the game as it exists today. The interactive planner lives in the Magic Craft Companion.
Recipe availability
Enchanted Mage's Gem is a rank 3 Magic Craft recipe with a best success rate of 99% at rank 1 and dan ranks.
Materials
Each craft uses
7× Verdant Mage's Gem — Trade 1 Bri Leith Obol to Leannan after clearing the Bri Leith raid.
20× Mana Stone — Have a Hillwen Engineer or Magic Crafter produce it as a Soul Liberator component.
20× Gemstone Powder — Fragment any Ascension Gem such as Jade or Opal for a chance at it.
10× Awakened Strength Powder — Buy from Stewart's Secret Shop for 50,000 gold.