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Reeded Edge, Reeding

Reeded Edge, Reeding.  Alternating ridges (knurls) and indentations (flutes) on the edge of a struck numismatic piece. In addition to reeding, the series of ridges and indentations is also called knurling. This edge treatment should not be confused with milling or upsetting – processes for smoothing the edge in preparation for striking. Originally reeding was used to prevent coins from being shaved – it is somewhat of a security edge – but also assists in constant handling, in picking up a piece by hand, for quick identification by blind persons, also for counting, sorting and other reasons.

            A single reed is one knurl and one flute, collectively many reeds, as all those on a coin, is the reeding. Reeding must be perpendicular to its obverse and reverse surfaces in order to effect this ejection – parallel ridges or any other configuration of edge designs as lettering or ornamentation obviously could not be ejected. (enough not to mash the edge ornamentation.)

When the reeding extends around the complete circumference of the struck piece it is known as fully reeded. When one or more areas of the collar are smooth, causing one or more smooth areas on the struck piece, this is called interrupted reeding. Generally interrupted reeding has one smooth area at the bottom (6 o'clock) position, or the top (12 o'clock) position to allow for edge marking there. See edge lettering and numbering. Beginning in 1965 the Franklin Mint has utilized a system of many different interrupted reeding patterns to identify gambling tokens by observing the smooth and reeded edges, a distinctive number of these for each issuing casino (a separate collar was created for each).  See interrupted reeding.

How reeding is formed. A reeded edge is produced by a reeded or grooved collar; the reeding on a coin is created at the same instant the piece is struck by a pair of dies. When struck, metal of the blank fills every cavity of both obverse and reverse die, it also expands between the dies up against the reeded collar filling every indentation and forming the knurls and flutes. The piece is then pushed out through these channels in the collar by the ejecting mechanism of the coining press. One of the dies must be engineered to extend past the edge of the collar to push out – eject – the struck piece.

            Reeding as diagnostic. Because reeding is so tied to the collar that forms it, this becomes obvious when the same item is struck at different times or at two different mints using different collars. The later occurred in 1968 when the Canadian 10 cent piece was struck both in Ottawa and Philadelphia. The Canadian Mint furnished the dies, but not the collars to Philadelphia. Philadelphia used collars they had on hand for a dime size coin. The only difference, then, was the reeding.


            History of reeding. Reeding was originally imparted to coin blanks before striking by the use of the Castaing machine (14th century). The rise of the use of the collar – in the 15th century – eliminated the use of the Castaing machine (except for ornamental or engrailed edges).

            Cataloging reeding. Generally reeding is not mentioned in cataloging. But astute numismatists must be aware if the reeding differs among two or more specimens. Then a reeding count must be taken and reported in any cataloging.

See collar (2).

excerpted with permission from

An Encyclopedia of Coin and Medal Technology

For Artists, Makers, Collectors and Curators


Roger W. Burdette, Editor

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