Star Ruby

Star Ruby is a mineral.

Source
Star Ruby can be mined from several deposits and drops from many high level mobs. It can also be prospected from Mithril Ore, Thorium Ore, and Iron Ore (rarely).

Star Ruby as an ingredient
Star Ruby is used in the following recipes:

Blacksmithing

 * Bloodsoul Breastplate
 * Bloodsoul Shoulders
 * Dawn's Edge
 * Demon Forged Breastplate
 * Ebon Shiv
 * Fiery Plate Gauntlets
 * Heartseeker
 * Imperial Plate Helm
 * Radiant Breastplate
 * Runic Breastplate
 * Runic Plate Leggings
 * Thorium Helm
 * Truesilver Breastplate
 * Truesilver Champion
 * Volcanic Hammer

Engineering

 * Bloodvine Goggles
 * Dimensional Ripper - Everlook
 * Gnomish Mind Control Cap
 * Goblin Jumper Cables XL
 * Hyper-Radiant Flame Reflector
 * Mithril Mechanical Dragonling
 * Rose Colored Goggles
 * Sniper Scope
 * Spellpower Goggles Xtreme
 * Spellpower Goggles Xtreme Plus

Jewelcrafting

 * Truesilver Commander's Ring
 * Ruby Crown of Restoration
 * Red Ring of Destruction
 * Figurine - Truesilver Boar
 * Figurine - Dark Iron Scorpid
 * Ruby Pendant of Fire
 * Figurine - Ruby Serpent

Tailoring

 * Inferno Gloves
 * Wizardweave Turban

Star Ruby as a quest item
Star Ruby is needed for the quest.