Expertization is the process of authentication

Authentication

Authentication is the act of confirming the truth of an attribute of a datum or entity...

 of an object, usually of a sort that is collected

Collecting

The hobby of collecting includes seeking, locating, acquiring, organizing, cataloging, displaying, storing, and maintaining whatever items are of interest to the individual collector. Some collectors are generalists, accumulating merchandise, or stamps from all countries of the world...

, by an individual expert or a committee of experts.

The expert committee will examine the collectible and issue a certificate typically including:

1. A statement of:
   1. Whether or not the item is authentic
   2. Identification of any damage to the item
   3. Identification of any repairs to the item
   4. Identification of any forgery or faked parts of the item
2. A photo of the item

Some experts will apply an experts mark, signature, or similar marking to the item to attest to its genuineness.

Expertization is particularly common with valuable philatelic items, some of which are so often forged that they may be unsaleable without an expert certificate confirming that they are genuine.