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.

Leatherworking: Bags
RecipeMakesReagentsNeedsSkill-up
Light Leather Reagent BagTaught by Pattern: Light Leather Reagent Bag, requires 30
Light Leather Reagent BagYellow 40Grey 50
Kodo Hide BagTaught by Pattern: Kodo Hide Bag, requires 35
Kodo Hide BagYellow 65Grey 95

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