Rarity

Rarity or at some point Quality is a property of Items, which is represented in-game by the color and name under the item's name and (in most cases) by a title prefixed to the item's name. An item can have only one rarity, which is determined when the item is created and remains unchanged, except in rare circumstances. An item with a higher rarity has a less drop rate, than an item with a lower rarity.

Rarity is a purely cosmetic property, and has no effect on gameplay other than some additional on-screen messages.

Strange
Strange is a quality introduced with the Dota 2 Store. Strange items are virtually all items that are obtained commonly from opening Treasure Chests. All Strange items have the capability of upgrading the rank prefix on their name, based on tracking a count of a specific in-game event, usually the number of players that the weapon has killed.

Colors
Ordered by rarity (from low to high)