Cardinal Ruby

This is the WotLK version of the Crimson Spinel, the epic red gem. Already in the game files, it has been officially introduced in patch 3.2.0, and can be obtained in the following ways:

• 
  
• prospected from Titanium Ore;
• 
  
• created by an alchemical transmutation using 1 Scarlet Ruby and 1 Eternal Fire;
• 
  
• sometimes found inside an Icy Prism created by a jewelcrafter;
• 
  
• bought for 20 Emblems of Heroism from Arcanist Ivrenne, Magistrix Lambriesse, or Harold Winston in Dalaran;
• 
  
• exchanged for 10,000 honor points from Captain O'Neal in Stormwind or Lady Palanseer in Orgrimmar.
• 
  

Cardinal Ruby can be cut in the following variations by a 450 Jewelcrafter (the respective designs can be bought from Timothy Jones in Dalaran, Inessera and Nemiha on the Aldor's Rise and Kirembri Silvermane on the Scryers' Tier in Shattrath for 4 Dalaran's Jewelcrafter's Tokens each):

• 
  
• Bold Cardinal Ruby: +20 Strength;
• 
  
• Delicate Cardinal Ruby: +20 Agility ;
• 
  
• Runed Cardinal Ruby: +23 Spell Power;
• 
  
• Bright Cardinal Ruby: +40 Attack Power;
• 
  
• Subtle Cardinal Ruby: +20 Dodge Rating;
• 
  
• Flashing Cardinal Ruby: +20 Parry Rating;
• 
  
• Fractured Cardinal Ruby: +20 Armor Penetration Rating;
• 
  
• Precise Cardinal Ruby: +20 Expertise Rating;
• 
  

Update (retail build 10192):

• 
  
• Updated the list of epic design vendors;
• 
  
• Corrected the design price from 5 to 4 Jewelcrafter's Tokens.
• 
  

Update (build 10072):

• 
  
• The uncut Cardinal Ruby's icon has been updated to match the actual gem color.
• 
  

Update (build 10048):

• 
  
• Epic gem transmutations now have a 20-hour cooldown.
• 
  
• Cardinal Ruby now costs 20 Emblems of Heroism, up from 15.
• 
  
• Transmute: Cardinal Ruby now requires 1 Scarlet Ruby and 1 Eternal Fire instead of 3 Eyes of Zul.
• 
  

Apparently you can no longer buy them from the Legacy Quartermaster in Dalaran anymore.

You can also use old Burning Crusade gems, Crimson Spinel, as they provide the same amount of stats, if those are easier available to you.