SRD:Appraise Skill

Check
You can appraise common or well-known objects with a DC 12 Appraise check. Failure means that you estimate the value at 50% to 150% (2d6+3 times 10%,) of its actual value.

Appraising a rare or exotic item requires a successful check against DC 15, 20, or higher. If the check is successful, you estimate the value correctly; failure means you cannot estimate the item’s value.

A magnifying glass gives you a +2 circumstance bonus on Appraise checks involving any item that is small or highly detailed, such as a gem. A merchant’s scale gives you a +2 circumstance bonus on Appraise checks involving any items that are valued by weight, including anything made of precious metals.

These bonuses stack.

Epic Check
You can also sense magical auras in objects.

Detect Magic
You can sense if an item has a magical aura. You can then use Spellcraft to learn more about the item as if you had already cast detect magic on the item.

Action
Appraising an item takes 1 minute (ten consecutive full-round actions). Detecting magic is a full-round action.

Try Again
No. You cannot try again on the same object, regardless of success.

Special
A dwarf gets a +2 racial bonus on Appraise checks that are related to stone or metal items because dwarves are familiar with valuable items of all kinds (especially those made of stone or metal).

The master of a raven familiar gains a +3 bonus on Appraise checks.

A character with the Diligent feat gets a +2 bonus on Appraise checks.

Synergy
If you have 5 ranks in any Craft skill, you gain a +2 bonus on Appraise checks related to items made with that Craft skill.

Untrained
For common items, failure on an untrained check means no estimate. For rare items, success means an estimate of 50% to 150% (2d6+3 times 10%).