From WoWWiki

Bonuses for Spirit can only be obtained through Blue gems, Green gems and Purple gems.

Color	Name	Effect(s)
Blue	[Sparkling Zircon]	+4 Spirit
	[Sparkling Azure Moonstone]	+6 Spirit
	[Sparkling Star of Elune]	+8 Spirit
	[Sparkling Empyrean Sapphire]	+10 Spirit
	[Sparkling Falling Star]	+12 Spirit
Green	[Seer's Chrysoprase]	+5 Spirit	+4 Intellect
Purple	[Purified Jaggal Pearl]	+3 Spirit	+7 Healing
	[Unstable Sapphire]	+4 Spirit	+9 Healing
	[Purified Shadow Pearl]	+4 Spirit	+9 Healing
	[Imperial Tanzanite]	+5 Spirit	+9 Healing
	[Fluorescent Tanzanite]	+4 Spirit	+6 Spell Damage