Diagnostic Controls & Presets Blakesley Effect Forensic Authenticator
Diagnostic Forensic Readings
Forensic Attribution Diagnostic
Real-time metallurgical and die variety cross-examination verified against certified populations.
Technical Breakdown: Physics, Metallurgy & Die Diagnostics
Clipped planchets are genuine mint errors created when metal strip feeds through the blanking press too slowly, causing the cylindrical blank-cutting punch to overlap a hole from a previously punched blank. The missing crescent produces two undeniable physical signatures that counterfeiters cannot duplicate: rim tapering and the Blakesley Effect.
Before coins are struck in coining dies, circular blank planchets pass through an upsetting mill (two grooved counter-rotating wheels) that squeezes the edge to raise a protective rim.
When a clipped blank rolls through the mill, the absence of metal in the clip causes the upsetting wheel to lose traction and radial compression when contacting the void. Consequently, the edge directly OPPOSITE the clip (180°) receives zero mechanical pressure, resulting in a flat, weak, unformed rim called the Blakesley Effect.
During the strike, planchet metal flows outward toward the collar. Adjacent to a genuine clip, the raised rim gradually tapers down to a feather edge. Fake clips made with wire cutters cut squarely through fully formed rims without any gradual tapering.
Documented Benchmark Auction Records
PCGS MS-64. Large 12% curved clip error on a 90% silver half dollar with textbook Blakesley rim collapse opposite the clip.
PCGS MS-63. Spectacular double-clip error showing twin overlapping crescent punches and dual Blakesley effects.
PCGS MS-65. Rare straight clip on an uncirculated 40% silver large dollar struck from the very end of the rolled metal coil.
Frequently Asked Questions
What is a clipped planchet error?
A clipped planchet error occurs when a blank coin is punched out of a metal sheet that has already had blanks cut from it (curved clip) or from the ragged edge/end of the metal coil (straight or ragged clip).
What is the Blakesley Effect and why is it so important?
The Blakesley Effect is an optical rim weakness or flat spot found directly opposite (180 degrees) from a genuine clip. Because the clip creates a void, the upsetting mill cannot exert pressure on the opposite rim, proving the defect occurred BEFORE striking.
Can you fake a clipped planchet with wire cutters or tin snips?
People frequently try to fake clips by cutting coins with snips, but authenticators easily catch them: fake clips lack the Blakesley Effect at 180 degrees, display sharp square edges instead of tapered rims, and show tool marks and crushed metal.
What is the difference between a curved clip and a straight clip?
A curved clip has a circular, concave bite caused by overlapping a round punch hole. A straight clip has a flat, linear edge caused by punching a blank over the side or end of the raw metal coil.
What is a 'tapering rim' near a clip?
When a genuine clipped planchet is struck between the dies, metal flows freely toward the open clip void without resistance, causing the raised rim to gradually taper and fade to zero thickness. Fake cuts cut straight through a full-thickness rim.
Are clipped planchet errors valuable?
Common modern cents with minor clips sell for $10 to $25. Choice 15% to 30% clips on quarters or dimes bring $75 to $200, and large clips on silver dollars, half dollars, or gold coins command $500 to over $2,000.
Can a coin have more than one clip?
Yes! Multiple clips occur when the punch overlaps two or three previous holes, creating dramatic 'double clipped' or 'triple clipped' planchets that carry significant collector premiums.