Mesmer Attires:
The default color of the Mesmer attires is green. Where it's green can it be dyed another color.
The default Mesmer Attires are called Stylish Attire. They confer no bonuses apart from the other attires.
Enchanter's Attire - Avaliable starting at Henge of Denravi. Confers +7 total Energy more than the other Mesmer attires.
Rogue's Attire - Available starting at Yak's Bend. +10 Armor vs. Physical attacks but -4 total Energy compared to the other mesmer attires (Enchanter's excluded).
Courtly Attire - Available starting at Yak's Bend. +15 Armor when casting.
NOTE: Only female Courtly Attire captured (my character Renebelle) and it's dyed purple.
Performer's Attire - Available starting at Lion's Arch. Same bonuses as Courtly Attire. It just looks different. The female attire looks similar to the default Stylish Attire for instance. No screen shots available of either yet.
Virtuoso's Attire - Available at the Black Citadel. This is the 15k version of the Performer's Attire so it has the same stats.
NOTE: The screenshots above were captured from the PvP Character creation section. I've seen female Virtuoso's Attire in the PvE game on some characters and I noticed they had 3 long plume feathers sticking out of the characters left shoulder. I don't know why it doesn't show here but aside from that, that's how Virtuoso's looks in game.
Noble Attire - Available at the Black Citadel. This is the 15k version of the Courtly Attire so they have the same stats.
NOTE: This is the NPC Mesmer Eludine at Serenity Temple. I haven't actually seen anyone wearing Noble in the game but based on what I saw on the Crafter's window, this is what it looks like. Basically it's Courtly with more gold designs on it. No screen captures of the male version.
Here's a front and back comparison of Courtly and Noble female versions.
The 15k versions of Enchanter and Rogue are available at Marhan's Grotto. They are called the same as their 1.5k counterparts and look identical as well. My guess is that they're placeholders for future Mesmer attires.
Imposing Mask - Available starting at Yak's Bend. +1 to Domination
Sleek Mask - Available starting at Yak's Bend. +1 to Fast Casting
Costume Mask - Available starting at Yak's Bend. +1 to Illusions
Animal Mask - Available starting at Yak's Bend. +1 to Inspiration
That's all.