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: Camping
RecipeMakesReagentsNeedsSkill-up
Camp Tent
Camp TentYellow 20Grey 25
Tanning RackTaught by Blueprint: Tanning Rack, requires 140
Tanning RackYellow 140Grey 145
Sewing MachineTaught by Blueprint: Sewing Machine, requires 300
Sewing MachineGrey 300

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