Blakesley effect : At the pole opposite a trot you ’ ll often find the invention rim to be watery or lacking and the edge to be unusually wide. Designated the Blakesley Effect ( after its inventor ), it can be seen on the illustrate 1965 Washington quarter dollar opposite each of the two small curved clips located respectively at 12:30 and 3:00 .
During upsetting — when a blank is rolled and squeezed into a planchet — the latter ’ s proto-rim can merely form when there ’ randomness resistor at the opposite punt. Any pause in the blank ’ south round sketch will briefly eliminate that resistance, preventing formation of the proto-rim. The planchet besides bulges out in this area, creating a close fit with the collar. As a consequence, the blueprint rim fails to strike up properly while the edge is particularly well-struck .
The Blakesley Effect is much absent in the case of big clips. That ’ second because the dies ’ affect is concentrated on a a lot smaller piece of metal, boosting the effecting contact atmospheric pressure. This increased fall upon pressure overcomes the miss of a proto-rim and generates a normal plan rim .
metal flow : design elements bordering a clip frequently show metal flow. In our 1965 Washington quarter dollar, the letters ER DOLL are stretched out and distorted. Metal menstruation results from coin alloy squeezing out from beneath the die as it follows the way of least resistance .
receding and candle of the design rim : As the design rim approaches a cartridge holder it will taper and fade out. metal that should normally rise to fill the flange gutter rather flows toward the break in the planchet. The reverse face of a 1972 Lincoln penny shows the impression at both ends of a minor curl snip .
Reversal of cut-and-tear border texture : The former three diagnostics are useful for any kind of clip ( curved, elliptic, straight, or ragged ). In fact, they can be used to authenticate any type of interruption in the circular sketch of a mint, provided that pause occurred before the strike .
Our last diagnostic is, however, only useful for curved ( concave ) clips and is best seen on dress coins where one takes advantage of a proxy phenomenon — a reversal in the asymmetrical exposure of the copper core .
When a blank die ( punch ) pushes through the coin metallic strip, the sharp edge of a trap in a perforated free-base plate slices through the bottom half of the stick out blank, producing a relatively smooth texture on the lower half of the blank ’ sulfur edge. As it ’ sulfur pushed even deeper into the base plate fix, the blank finally tears free, leaving behind a rough, farinaceous texture along the upper half of the blank ’ south edge .
The process is reversed for the hole that ’ mho left in the coin metal strip. The sharp edge of the blank die slices through the upper separate of the leach, leaving a placid texture along the upper half of the hole ’ south edge. When the blank tears free of the strip, it leaves behind a rough texture along the lower half of the hole ’ sulfur edge. A blank with a curved clip has part of a hole along its edge, where the edge texture is inverted relative to the convex dowry of the lacuna.
In invest coins, the lower clothe level is dragged partially over the edge of the blank as the latter is forced into the fix in the base plate. This results in asymmetrical exposure of the copper core. The hole in the clad clean shows the antonym form, where the upper clothe layer is dragged partially over the edge of the hole by the blank die .
The smaller of the two curved clips in our 1965 Washington one-fourth dollar shows the expected reversion in the asymmetrical photograph of the copper core .
In an egg-shaped ( convex ) clip, there will be no reversal in edge texture/core photograph because the trot edge experiences the like stresses as the normal edge of the blank .
In other types of clips, the edge texture/core exposure convention is besides variable and diverse to be of much habit .
Taken alone, none of these four diagnostics is goofproof as all are variable in their formulation and presence. But I ’ ve never seen a actual trot in which all four were absent. Therefore, even if only one of the four diagnostics is present, you can be confident your cartridge holder is actual. But if all four are lacking, you ’ rhenium looking at either post-strike damage or a strickle clip .
Coin World ’s Collectors’ Clearinghouse department does not accept coins or other items for examination. Materials sent to Clearinghouse will be returned unexamined. Please address all Clearinghouse inquiries to [email protected] or to 800-673-8311, Ext. 172.
More from CoinWorld.com:
Collector discovers new variety for 1896 Indian Head cents
2015 Special Silver Set ‘Currently Unavailable’ from United States Mint
‘Rarest silver coin of German Empire’ offered in Künker sale
Finding a Kennedy half dollar in circulation
How one group is putting $100,000 in dollar and half dollar coins into circulation
Keep up with all of CoinWorld.com’s news and insights by signing up for our free eNewsletters, liking us on Facebook, and following us on Twitter. We’re also on Instagram!