Each recipe is orange until its yellow rank and grey from its grey rank. When the ranks differ, it turns green somewhere between the two; the client files give both ranks but not that point. Equal ranks go straight to grey.

Alchemy: Weapon Oils
RecipeMakesReagentsNeedsSkill-up
Shadow OilTaught by Recipe: Shadow Oil, requires 165
2 × Shadow Oil
  • Fermenter
Yellow 190Grey 230
Frost OilTaught by Recipe: Frost Oil, requires 200
2 × Frost Oil
  • Fermenter
Yellow 220Grey 260

From the Forever beta client files, build 1.60.1.70630: the SkillLine, SkillLineAbility, TradeSkillCategory, SpellReagents, SpellEffect, SpellTotems, SpellCastingRequirements and ItemEffect tables.