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Last Updated 06/24/13

Articles by Ken Potter

"Near 6" & "Far 6" Date Varieties on Canadian 1996 Five-Cent Pieces Examined

Discolored Sac & Prez Dollars -- What Are They?

2009-P-D-S District of Columbia Doubled Die Listings

1999-W 1/10th Eagle $5.00 Gold Matte Finish Error or Variety?

Authenticating 'Silver Pennies'

2005-P Minnesota "Leaping Fish"? - Ohhh! No! They Arn't!

States Quarter Die Chips, Breaks, etc. -- Error or Variety?

New Yorker Gets Error Proof Set Birthday Surprise!

Second 1982 Doubled Die Reverse Uncovered By Reader

Collector Finds Double Struck Dollar Error In Gov. Issued Mint Set!

Doubled Die Art Medal Designed Felix Schlag

1980-D&S Lincoln Cent Debunked

List of Proof Spiked Head Varieties Grows 

1969-S Doubled Die 1c Roll Find May Hit $100,000

"Fresh" 1969-S Doubled Die Obverse Lincoln Cent Found In Roll

PCGS Certifies 1969-S Doubled Die Cent by PCGS

Weak Edge Inscription Jefferson Dollar Found

The Exceedingly Rare Canada 1965 Large Beads 5c Revisited 

Canada 1965 "Extra Bud" Doubled Die Cent

Clipped Planchet Jefferson Dollars Certified by PCGS

Leaf-Shaped Die Dent Found On Minn. 25c

1999 1c "Wide AM" Reverse Die Study

2007-P Thomas Jefferson Doubled Die Reverse Found

2007-P Thomas Jefferson Dollar Doubled Die Reverse Found!

Wisconsin Quarter Die Hardness Tests Debunked

Two Headed Coin Unlucky for Some

2006 Lincoln Doubled Die Found Second Strong Variety Reported For Year!

Washington $1 Exhibits Tilted Edge Lettering

1999 1c "Wide AM" Reverse Die Study

Double, smooth edges on 2007-P Adams

New error dollar appears; Edge of Adams coins impressed twice

D-Mint Plain Edge Dollars Might Be Told Apart From P-Mint Dollars

Plain Edge Errors Found In Denver Mint Rolls

PCGS certifies lettered-edge planchet

George Washington "Golden" Dollar Sports Die Gouge

The Illustrated Oregon 25c Doubled Die Listings

Minnesota Quarter Doubled Die Obverse Found!

Doubled Die Oregon State Quarter Found!

Proof  Minnesota Quarter Doubled Die Found!

PCGS Will Certify Minnesota Quarter Varieties

2005-P-D-S Minnesota Doubled Die Listings

2005-P Minnesota Quarters Boast Extra Tree

1970-S Small And Large Date Cent Diagnostics

2005-P-D-S Minnesota Doubled Die Listings

Differentiating 1979-S & 1981-S Mint Mark Types

Doubling: Distinguishing The Valuable From The Worthless

Is My 1969-S Lincoln Cent "The" Doubled Die?

1997 "Double Ear" - Doubled Die Cent Diagnostics

1998, 1999 & 2000 Type-2 "Proof Style Reverse" Lincoln 1c Diagnostics

Bison drops letter From Numismatic News

1999-S Proof 1c w/Circulation Style Reverse Discovered

What A Major Die Break (Cud) Is & What It Isn't!

2005-S KS Proof 25c Hoof-Shaped Die Dent vs. Alleged Wisconsin High/Low Leaf Vars.

Bahamas 1975-1973 Dual Dated 5-Cent Variety Discovered!

New 1900 Morgan Dollar Doubled Die Reverse Discovered

Matte Unc 2005-P Bison Five-Cents Doubled Die Obverse Found!

Matte Unc 2005-P Ocean In View 5c Doubled Die Obverse Found!

The 1979-81 American Hostage Crisis As Recorded In Numismatics

The Rise And Fall Of Spuds MacKenzie As Recorded In Numismatics

Doubled? Quadrupled? Quintupled? Sextupled Die? Finland 1947-S 1 Marrka

1984 Olympic Dollars Sport Deceptive Strike Doubling

In-depth Analysis Of The Wisconsin Quarter Variations

Is My 1958 Cent A Doubled Die?

The 2004-P Doubled Die Nickel Examined

The 1964-D Doubled Die Rev Dime (The Big One!)

The 1964-D Doubled Die Rev Dime (The 2nd Big One!)

2003 Lincolns Found With Wavy Steps

1950-D/S Over Mint Mark Franklin Half Discovery Confirmed

Those Fantastic States Quarter Errors!

Significant 1994 Doubled Die Reverse Lincoln Cents

Die Adjustment Strike Or Weak Strike?

Die Adjustment Strike Or Weak Strike? by Sean Moffatt

Major 1946 Doubled Die Roosevelt Dime Found

1955-S Cud Reverse / "Capped Head" Obverse Cent

Interesting Die Clashes With Raised Details In Design

Libertas Americana "Nonsense" Metallurgical Trials

1934 Lindbergh Trial Cents - What Are They?

Is It A Coin Or Medal? -- An Opinion

Major Italian Doubled Die Obv/Rev Found In Pocket Change

About Contaminated Die Design Transfer Errors

"Raised Image Strike Doubling" on 1992-P Jeffersons

Diagnostics Of Curved Clip Errors: How To Authenticate Them

1918-S Standing Liberty Quarter "E" Die Clash

1937 Doubled Die Obverse Quarter Diagnostics

1959 High Over Low Relief Eagle Double Die Reverse Half

Canada 1948 & 1949 Obverse Cent Varieties

Chinese Cash Sports Four-eyed Dragon

Selected 1962 Doubled Die Obverse Lincolns

1936-D San Diego 50c Repunched Mint Mark Report

1936 Cleveland Great Lakes Exposition
Commemorative Half Dollar Doubled Die Obverse

1935 Daniel Boone Bicentennial
Commemorative Half Dollar Doubled Die Obverse

1963-D 50c Doubled Die Obverse Reported

1950-S 25c Doubled Die Reverse Reported

1954 25c Doubled Die Reverse Reported

Gasparro's 1977 Flowing Liberty Head $1 Trial

Germany 1989-F 1 Deutsche Mark Doubled Die Obverse Reported

Attribution Guide to 1974 Canadian Nickel Dollar Varieties

11-Cent Pieces Explained

Articles by Ken Potter - Coin Universe/PCGS Author Index

Proof  Minnesota Quarter Doubled Die Found!

PCGS Will Certify Minnesota Quarter Varieties

2005-P Minnesota Quarters Boast Extra Tree

So Just When Did Single-Squeeze Hubbing Begin?

Recent Finds Series (CONECA Web Site)

"Oh, No It Ain't ...!!" Series (CONECA Web Site)

1998 American Silver Eagle 7-Coin "Strike Thru" Progression!

The Canada 1991 Snowy Owl $300 Doubled Dies

Spiked Head Watch! (A Listing of "Spiked Head" & Related Die Cracks on Proof Coins)

Cortez Reports Honduran Overdate w/ Monster Doubled Die

Diagnostic Features Of The 1922 "No D" 1c Die Pair#2

1964 Coins Minted For Three Years!

German 1939-D 2 Reichspfennig Doubled Die

Treatment of Minor Varieties

Look For 2002-S "Spiked Head" Silver-Proof JFKs

Links To Articles by Other Authors

A Look At The 2000 MAD Clash Cent (Formerly Called The “Extra Beard” Doubled Die) by BJ Neff

The 1968-S ''No S'' Proof Dime by Jaime Hernandez

Oops. . . Richard Giedroyc

Zinc 1982 Cent Host To New Doubled Die by Charles D. Daughtrey

Determining Die Doubling from Other Forms of Doubling by J.T. Stanton, NLG

A Die Clash Rating System by The Ike Group

Determining Die Doubling From Other Forms Of Doubling by J.T. Stanton, NLG

Mint to 'tweak' processes to cut errors by Numismatic News

PCGS Certifies Blank Planchet, Lettered-Edge Presidential Dollar by PCGS

The Faceless Dollar Joins the Growing List of Major Washington Dollar Errors by Susan Headly

Presidential Dollars Fraud Report - Beware of "Buffy Dollars"

Washington Dollar Plain Edge Coins - FAQs

A Comprehensive List Of Reported GW Dollar Errors

Richard’s ROOSEVELT Dime Review

Cherrypicking by Eric von Klinger

The Minting Process by Birmingham Mint

Cent's reverse rotated From Numismatic News by Billy G. Crawford

Opinions continue to vary on cause of odd marks on Wisconsin quarters  by Coin World

Coveted quarters common after all? by Tucson Citizen

Wisconsin excitement grows by Coin World

Wisconsin "extra leaf" quarters -- my analysis by Mike Diamond

Prices rising for Wisconsin quarters with extra 'leaves' by Coin World

PCGS Grades Wisconsin State Quarter Major Varieties by PCGS

Sacagawea $1 has Two Hubs by Coin World

The CONECA Top 100  Lincoln Cent RPMs by James Wiles

A VERY Special Susan B. Anthony dollar!

The CONECA Top 100 Jefferson Nickel Varieties Listing by James Wiles & Jason Taylor

Double Struck 1904 Gold Double Eagle by Heritage

Found Treasures: 1914/3-S Nickel by Stewart Huckaby (Heritage)

1795 $1 Flowing Hair, Two Leaves. Struck over previously struck 1794 silver dollar by Heritage

1823/2 25c VF30 NGC. B-1, R.6. in ANA Sale by Heritage

1916 5c Doubled Die Obverse AU58 Realizes $39,000 by Heritage

"Superbird" Quarter Pair at Pittsburgh ANA Signature Auction by Heritage

The 2004-P Doubled Die Nickel by Jason Taylor

The 2004-P Doubled Die Nickel by Billy Crawford

Buffalo Nickel Errors and Varieties at Long Beach by Heritage

Varieties (Over Mint Marks, etc.) On Modern Coins Of India by Paul Baker

How Coins Are Made by US Mint

Seldom Seen Selections: 1856 Flying Eagle Cent, Snow-5

Found Treasures: 1859 Transitional Dime

Shades Of Silver - Art bar collectors seek the best by Paul Gilkes/Coin World

2003-S Proof Sacagawea Dollar "Spiked Head" Error by

Fey Finds 1796 Dime With Repunched 6 from Numismatic News

Spiked Jeff Head Seen! from Numismatic News

Proof 2002 Nickel "Spiked Head" Die Break by Bill Penner

Coinage Struck On Foreign Planchets by Gregory N. Mirsky

About 1943 "Copper" Cents by Alan Herbert Article Index on Error Coins Article Index on Variety Coins

PCGS Library Article Index for Alan Herbert

PCGS Library Article Index for Ken Potter

CONECA Error-Variety Coin Articles Index

PCGS Article Index For Errors

PCGS Article Index For World Errors

PCGS Article Index For Varieties

PCGS Article Index For World Varieties

US Small Size Dollar Coins & Related Items by Mike Wallace

Early Die State MS66 1914/3 Buffalo Nickel by Heritage

Found Treasure: 1823/2 Quarter by Heritage

Mint Tour by Frank M. Zapushek

Canadian Paper Money Errors Explained by Tom Merritt

Author's Index for Alan Herbert

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Ken Potter
P.O. Box 760232
Lathrup Village, MI 48076-0232

  Phone: 1-(313)255-8907   E-mail:

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Numismatist Since 1959 ~ Serving the Collector Since 1973
CONECA's Longest Serving Doubled Die Attributer

  Member of:  ANA    CONECA-LM  NLG   NCADD-FM   MSNS-LM

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Unless otherwise stated, all Photographic Images are by Ken Potter.   Copyright Ken Potter, 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2001.  Use of images in any manner is strictly prohibited without the express written permission of the copyright holder.

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