What is lost and gained by going prestige?

The rewards for prestige are as follows:

• Prestige 1 Prestige Leaderboard, Custom Class 6
• Prestige 3 Custom Class 7
• Prestige 5 Custom Class 8
• Prestige 7 Custom Class 9
• Prestige 9 Custom Class 10
• Prestige 11 Face Tattoos
• Prestige 13 Clan Tag Colors
• Prestige 14 Golden Camo
• Prestige 15 Prestige Playlists

Apparently you lose everything except for emblems.

I can confirm that you don't lose absolutely everything when prestiging.

Some of the things I've noted you don't lose:

• Layers, shapes, and the "banner" for your playercard/emblem
• If you bought the emblem or clan tag option for guns, this is not lost when you repurchase the gun(as in, you don't have to rebuy the emblem/clan tag for the gun)
• Camo for guns is not lost, so you don't have to rebuy them. (But you do have to wait til the appropriate level to equip them)
• (unconfirmed) face paint is not lost, so you don't have to rebuy it.

The important thing to me that IS lost is pro perks. You have to start from scratch and complete the challenges all over again(along with actually buying the pro perk). I consider this a design flaw, but it's the way it works.