Expertization is the process of authentication of an object, usually of a sort that is collected, by an individual expert or a committee of experts.

The expert committee will examine the collectable and issue a certificate typeically 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.

Philatelic expertization

The hobby of stamp collecting makes extensive use of experts committees.

An example of what may be considered by an experts committee for a cover would include:

  1. The cover itself:
    1. Are there any repairs to the cover
      1. Sealed tears
      2. Stains removed by bleaching
      3. Cutting down one side of the envelope to remove a torn edge where the envelope was opened
      4. Erased pencil marks written by earlier stamp collectors
    2. Is the cover faked:
      1. Is the paper from the time period when the cover went through the mail?
  2. The stamps on the cover:
    1. Are the stamps genuinine or forged?
    2. Are the stamps correctly used? For example, using a stamp years after it is no longer valid for postage
    3. Have the stamps been repaired (cleaned, bleached, reperforated)?
    4. Have the stamps been removed from the cover and reglued to it? Usually done to identify rare varieties of the stamps
    5. Have stamps been removed from the cover?
    6. Have stamps been added to the cover which were not present when the cover passed through the mail? For example, adding a rarely used stamp to an existing cover to make an ordinary cover extremely valuable
    7. Have the stamps been removed and replaced with different stamps? For example, removing a stamp in excellent condition and replacing it with one having damage to the back, giving that the damaged backside of the stamp will not be visible.
  3. The postal markings on the cover
    1. Are the postal markings genuine?
    2. Are the postal markings appropriate from the time period used?
    3. Have extra faked postal markings been added to the cover to make it more valuable?
    4. Is the ink genuine and from the time period used?

In the US, the Philatelic Foundation and the American Philatelic Society have committees who will perform expertization for a fee. In Europe and other places, individual experts advertise their availability, expertize items sent to them, and sign the items that they've evaluated.

The result of expertization may be challenged; in some cases further research has shown the genuineness of an item considered a forgery, or vice versa. Experts often recommend that valuable items be re-certified every 10-20 years.