how bout legendary item??? What colour is that?? For what use??

Inferior[gray]: These items are intended to be sell-able (or possibly salvageable) items and are not normally worn by the player. Also referred to as "junk".

Common [white]: Most normal items have no attributes associated with them unless they are of superior quality. They are the base item to be modified by other qualities.

Magic [blue]: Magic items have a few affixes on them that are reflected in the name of the item. For example, on the boots pictured at right, "Ornate" applies a +150% gold sell value to vendors and "of Accuracy" gives the boots an additional dexterity modifier.

Rare [yellow]: Rare items are better magic items, spawning with more random properties. Blizzard has stated that they want rare items to have a chance to be better than legendary items because of the random modifiers.

Legendary [gold]: Legendary items replace Unique Items from Diablo II. They are powerful items with many preset properties that always appear on the same legendary items, though they also come with a few random properties that differ between items.

Set [green]: Set items are similar to legendary items except they also provide additional properties if you equip items of the same set. Some set items can be crafted by an Artisan after finding corresponding recipes or dropped as regular loot at end-game.

No use picking up Grey/White items. You sell them also 2-3 Gold each. Better off collecting Blue/Yellows all the way and throwing out White/Grey if you accidentally picked them up.