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: Miscellaneous
RecipeMakesReagentsNeedsSkill-up
Heavy Leather BallTaught by Pattern: Heavy Leather Ball, requires 125
Heavy Leather BallYellow 125Grey 135
Gordok Ogre Suit
Gordok Ogre SuitYellow 285Grey 295

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