How do I complete the 'Attention to Detail' achievement?

The achievement is called "Attention to Detail" which made me believe there must be a difference in their looks... but only if you're paying attention.

I found some comments over at WoWHead that indicate the boss's mirror images are slightly different. I will copy in some of these comments.

Option 1: Look closely!

You can look at them and pay close attention:

CORRECT ILLUSION
Black headband,
Black hair that goes over her shoulder, 
Black chestpiece
Black shoulders

BAD VARIATIONS INCLUDE
White shoulders
White hair
Short hair
Sapphire-White headband
Ruby-White headband
White Chestpiece

Option 2: Macro/chatbox solution

You can also make a nice macro (or type a script into chat) that will show you the model of the original boss alongside a model of your current target, which should help with quickly identifying the right one:

First, this one:

/run frm = CreateFrame("PlayerModel");frm:SetPoint("BOTTOMRIGHT",nil,"BOTTOMRIGHT",0,100);frm:SetHeight(600);frm:SetWidth(300);frm:RegisterEvent("PLAYER_TARGET_CHANGED");frm:SetScript("OnEvent",function(self,event,...) frm:SetUnit("target") end);

It will show a huge model of your current target at the right of your screen.

Then, target the boss and use that one:

/run frm2 = CreateFrame("PlayerModel");frm2:SetPoint("BOTTOMRIGHT",frm,"BOTTOMLEFT",0,0);frm2:SetHeight(600);frm2:SetWidth(300);frm2:SetUnit("target")

It will display the original boss next to your current target.

After that, the achievement should be easy

And to deactivate the model box:

/run frm:UnregisterEvent("PLAYER_TARGET_CHANGED");frm:Hide();frm2:Hide()