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: Reagents
RecipeMakesReagentsNeedsSkill-up
Light Leather
Light LeatherYellow 20Grey 40
Cured Light Hide
Cured Light HideYellow 50Grey 70
Medium Leather
Medium LeatherYellow 75Grey 85
Cured Medium Hide
Cured Medium HideYellow 90Grey 105
Heavy Leather
Heavy LeatherYellow 125Grey 135
Cured Heavy Hide
Cured Heavy HideYellow 135Grey 145
Cured Thick Hide
Cured Thick HideGrey 175
Thick Leather
Thick LeatherYellow 175Grey 180
Rugged Leather
Rugged LeatherGrey 225
Cured Rugged Hide
2 × Cured Rugged Hide
  • Tanning Rack
Yellow 225Grey 235

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

One more recipe in this category is encrypted in this build.