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.

Enchanting: Amulet Enchants
RecipeMakesReagentsNeedsSkill-up
Enchant Necklace - AgilityTaught by Formula: Enchant Necklace - Agility, requires 210
  • Runed Truesilver Rod
Yellow 225Grey 265
Enchant Necklace - DeflectionTaught by Formula: Enchant Necklace - Deflection, requires 210
  • Runed Truesilver Rod
Yellow 225Grey 265
Enchant Necklace - Healing PowerTaught by Formula: Enchant Necklace - Healing Power, requires 210
  • Runed Truesilver Rod
Yellow 225Grey 265
Enchant Necklace - Spell PowerTaught by Formula: Enchant Necklace - Spell Power, requires 210
  • Runed Truesilver Rod
Yellow 225Grey 265
Enchant Necklace - StrengthTaught by Formula: Enchant Necklace - Strength, requires 210
  • Runed Truesilver Rod
Yellow 225Grey 265

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