Pure Gemstone 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
Pure Gemstone is a rank 3 Magic Craft recipe with a best success rate of 98% at rank 1 and dan ranks.
Materials
Each craft uses
3× Enchanted Melding Agent — Buy from Leannan's shop in Bri Leith for 500,000 gold.
30× Gemstone Powder — Fragment any Ascension Gem such as Jade or Opal for a chance at it.
30× Teardrop Gem — buy from Trade Assistant Imp / Iria Trade Merchant for 35,000 Ducats
10× Purified Enhancer — Fragment an Infernal Blade Fragment or similar Hard Mode dungeon drop.