The Definitive Planchet Improper Thickness Errors Guide : EverRise Treasures

The Planchet Improper Thickness Errors Guide :

Improper Thickness of Planchet

The thickness of a coin is determined before the coin is struck, when large metal sheets or strips are passed through heavy rollers to reach the required thickness. If these machines are incorrectly set or fail to maintain the proper thickness, the resulting metal can be too thick or too thin. Blanks punched from such material may therefore produce coins that are noticeably heavier or lighter than the standard specifications for that denomination.

Another possibility is that a metal strip intended for a different denomination is accidentally fed into the wrong production line. Since different denominations can have different thickness and weight requirements, this can produce blanks that do not match the specifications of the coin being struck.

However, an unusually thick coin is not automatically a mint error. This is where the distinction between an accidental thick planchet and a Piedfort becomes important.

The Piedfort Distinction (It Is Not An Error)

A Piedfort is an intentionally manufactured coin that is generally made at approximately twice the normal weight and thickness of its regular counterpart, while retaining the same diameter and basic design. Unlike a thick-planchet error, its extra thickness is planned by the mint from the beginning.

Piedforts were never intended for ordinary pocket circulation. Historically, mints produced them as test pieces, presentation coins, or special gifts for royalty, officials, and other important individuals. In modern times, they have also been produced specifically for collectors.

India has its own Piedfort history. During the 1980s, the Government of India experimented with officially issued Piedfort coins for collectors, including special Proof sets that were priced at nearly twice the cost of normal sets and limited to one per person. The experiment was not particularly successful because collectors considered the sets expensive, so relatively few were sold. Today, genuine Indian Piedforts can be highly desirable because of their intentional limited production.

Piedforts Around the World

The Piedfort tradition is much more widespread internationally and has a long history, particularly in Europe:

• France: Historical Origin: France is generally regarded as the birthplace of the Piedfort tradition, with examples dating back to the 12th century. The French term piedfort literally means “heavy foot.” The Monnaie de Paris (French Mint) has produced such special pieces for centuries, including presentation issues for royalty, important individuals, and collectors.
• United Kingdom: The Royal Mint became one of the best-known modern producers of Piedforts. Since the 1980s, it has issued double-thickness proof versions of selected coins and commemoratives, particularly in silver and gold, specifically for collectors.
• China: From the late 1980s, China also began producing highly collectible double-thickness versions associated with popular series such as the Gold and Silver Panda and Lunar coins.
• Canada & Australia: The Royal Canadian Mint and Royal Australian Mint have also produced double-thickness commemorative and proof coins for collectors, showing that the Piedfort concept remains part of modern numismatic production.
• Russia, Netherlands & Hungary: These and other European countries have also produced Piedfort or double-thickness presentation pieces at various points in their numismatic history.

Why This Matters When Identifying an Error

The worldwide history of Piedforts shows why extra thickness alone does not prove that a coin is an error. A coin may be unusually thick because of an accidental planchet problem, but it may also have been deliberately manufactured that way by the mint.

When examining a suspected thick-planchet error, collectors should consider its weight, diameter, thickness, metal composition, denomination, date, and known mint issues. Evidence should support that the unusual thickness resulted from an unintended production problem rather than intentional manufacture.

In simple terms:

Thick by accident = possible planchet error.
Thick by design = Piedfort.


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