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Microscopic Analysis of the Unicorn Penny
This section presents a series of notable microscopic images of the Unicorn Penny (“UP2”), together with commentary and analysis. UP2 is also compared with a high-level forgery of a 1930 penny that utilised numeral transplantation to achieve the desired date. This comparison highlights the fundamental differences between a coin struck from a die (UP2) and a forged coin that relied on micro-welding techniques.
UP2 Examination
The images below show a cleanly presented UP2 coin under 40× magnification, with no obvious traces of numeral transplantation or surface interference. All numerals appear to be fully integrated with the surface of the coin, with no signs of gluing, welding, or attempts to conceal such activity using mud, dirt, or other substances intended to imitate ageing.
Closer microscopic examination using electronic digital microscopy reveals details that are not visible under a conventional optical magnifying lens.
Figure 1
Figure 1 shows the lower curve of the numeral “3” on UP2, viewed at an angle of 120° under 500× magnification. The numeral appears to be homogeneously fused with the coin surface along most of its curved edge (A), with no visible juncture. This supports the conclusion that the coin was struck, rather than altered after striking. Towards the termination of the curve, however, a small ridge becomes apparent and gradually increases in prominence (B). This ridge is also fused to the coin surface and is consistent with remnants of numeral transplantation - specifically, the excision of a numeral from a donor coin or hub during die preparation.
Figure 2
Figure 2 shows the further development of the excising ridge illustrated in Figure 1, under the same viewing conditions but at 600× magnification.
Figure 3
Figure 4
Figure 5
Figure 6
Figures 3 to 6 show different sections of the numeral “3” under a 40° viewing angle and 600× magnification. Homogeneous metallic fusion with the coin surface is evident along the entire length of the numeral, reinforcing the observation that the coin was struck. In certain sections, the excising ridge is expressed to varying degrees, ranging from clearly perceptible (A) to almost imperceptible (B).
Figure 7
Figure 7 shows the excising ridge on the leftmost numeral “1” under a 90° viewing angle and 500× magnification. The ridge is more pronounced along the rounded portions of the numeral (A) than along the straight sections (B), which is consistent with excision techniques, as cutting curved lines typically produces less uniform edges than cutting straight lines.
Another important point, addressed in more detail later, is that the width of the excising ridge measures only between 0.04 mm and 0.05 mm - approximately 45 microns.
Figure 8
A similar ridge (A) shown in Figure 8 is also observed along portions of the rightmost numeral “1” under a 40° viewing angle and 600× magnification. The homogeneous integration of the ridge with both the numeral and the coin surface is evident, further supporting the conclusion that the coin was struck rather than altered.
Below are microscopic images of UP2 under 800× magnification and various viewing angles, shown using both natural and ultraviolet illumination. Ultraviolet light was used to detect any evidence of gluing or surface interference at the junction between the numerals and the coin surface. No evidence of gluing or micro-welding is observed. On the contrary, seamless fusion is apparent, substantially diminishing - and arguably excluding - the possibility that the numerals were added after the coin was struck.
At magnifications of up to 1000×, the images below show the junction between individual numerals and the coin surface at a highly granular level and from various viewing angles. These images demonstrate continuous fusion between the numerals and the surrounding metal, with no indication of seams that would normally be present where numerals have been glued or micro-welded onto a coin. The observed structures are consistent with coins struck at the Mint.
Comparison with a 1930 Penny Forgery
Below are images of a high-level forgery of a 1930 penny, in which the numerals “3” and “0” were transplanted from a donor coin onto a 1929 Indian-obverse penny. A clear indicator of forgery is the presence of residue around the numerals, deliberately applied to disguise traces of interference. Notably, no such attempt to mask the numerals is evident on UP2, which is presented in an unmasked and pure state.
Under higher magnification, including the use of digital microscopy, clear signs of interference with the numerals on the 1930 penny become apparent.
Figure 9
Figure 9 shows that, at slightly increased magnification, traces of micro-welding are visible around the perimeter of the numeral “3”.
Figure 10
Figure 10 shows that after removal of the residue, a distinct juncture between the coin surface and the numeral “3” becomes visible (J). There is no true fusion between the numeral and the surrounding metal, indicating that the numeral was attached after the coin was struck.
The images below show additional defects associated with numeral transplantation, visible under high-power microscopy, including uneven excision of individual numerals and further traces of micro-welding.
Micro-welding
While the traces of micro-welding are clear on the 1930 forgery, it has been suggested by some that the ridges surrounding the numerals on UP2 are not remnants of excision, but instead evidence of a micro-welding seam. This claim can be tested directly through measurement and microscopic examination.
The microscopic ridge surrounding the numeral “1” on UP2 has an average width of approximately 0.045 mm (45 microns) and is remarkably uniform around the entire perimeter of the numeral (see Figure 11 below). Such uniformity and size of any welding seam would be fundamentally inconsistent with any known welding process. Even advanced laser micro-welding produces irregular bead widths, visible heat-affected zones, localised melting, and discontinuities - particularly when applied to copper, a metal with exceptionally high thermal conductivity.
In practice, the smallest continuous weld seams achievable with state-of-the-art industrial laser micro-welding are typically no less than approximately 80-100 microns, with narrower dimensions limited to isolated spot bonds rather than true perimeter seams.
The ridges observed in UP2 show no evidence of thermal disruption, porosity, bead overlap, or surface vitrification. Instead, they exhibit smooth continuity and consistent thickness at levels below the practical lower limit of even the most advanced industrial laser micro-welding systems.
The ridge is therefore incompatible with micro-welding and characteristic of metal displacement under pressure, i.e. consistent with the compression halo produced when a numeral, cut from a donor hub or punch, is pressed into a recipient hub during legitimate Mint die preparation.
Figure 11
Conclusion
Microscopic examination of the Unicorn Penny (UP2) demonstrates that the date numerals are fully integrated with the coin surface and exhibit structural characteristics consistent with a coin struck from a die. Across all magnifications examined, the numerals show homogeneous metallic fusion with the surrounding field, with no seams, voids, or discontinuities that would indicate post-strike attachment.
The presence of narrow, continuous ridges along portions of the numerals - measuring approximately 45 microns in width and exhibiting a high degree of uniformity - is incompatible with micro-welding or adhesive-based alteration. Such ridges show no thermal disruption, heat-affected zones, porosity, or bead irregularities, all of which are readily observed on known welded forgeries. Instead, these features are consistent with metal displacement under pressure, as occurs during legitimate die preparation involving the insertion of excised numerals into a hub or punch.
Direct comparison with a confirmed 1930 penny forgery further reinforces this conclusion. The 1930 example displays clear microscopic evidence of interference, including masked surfaces, visible junctures, uneven excision, and traces of micro-welding - none of which are present on UP2.
Taken together, the microscopic evidence supports the conclusion that the Unicorn Penny was struck from a Mint-prepared die and not produced through post-Mint alteration. The observed features align with established Mint manufacturing processes and are incompatible with known forgery techniques.
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The contents of this website are protected by copyright law. Copyright in this material resides with Dr. Y. Rapoport B.Sc SJD
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