- Adjustment lines or marks are traces of filing that reduced a punched coin blank to within the weight limits when coins were hand made. To understand what they are you need to envision the entire process used in the old screw press days.
Coin silver was poured into rather small molds making a thin ingot.
The silver ingot was rolled to coin thickness between two rollers.
A cookie cutter like apparatus then cut the coin blanks from the rolled strip.
A mint employee then weighed the blank. If it was too light it went back to the furnace with the other scrap. If too heavy - it was filed across the face to get it to the right weight.
Then the blank was edged with the appropriate anti-counterfeiting design which also upset the rim.
Then the planchet (as it was then called) was struck in an open sided screw press.
If the pressure was too slight or the filing marks too deep - they survived the strike. These are the adjustment marks seen on the coin.
The deep adjustment marks observed on colonial coins gradually disappeared as technology associated with rolling the ingots improved.
This process was used on US coins
until about 1836 - Mexican 8Rs until about the 1870s and on most other world coins at various periods of time.
Adjustment marks are often confused with post strike damage and at other times post strike scratches will be erroniously called adjustment marks. The difference can mean a significant difference in value. Morgan Fred
I presume that you meant planchet, flan or blank instead of die. Each individual planchet was weighed and if over weight one or both surfaces were filed to get it within tolerance. Edges were never filed. The dies were filed at various times for different reasons. But a scratch in the die produces a raised line on the coin. Adjustment scratches or lines are incuse.
They are prevalent on larger older coins where there was a high intrinsic tolerance. Smaller coins like dimes and 2R coins were almost in a token class so intrinsic contents were often not as critical and flans on smaller coins were often light.
This fact, that lower denomination coins were often undervalued when compared to the Dollar sized coins, was not obvious to most average people. It is why sharp merchants wanted payment in 8R sized coins or pieces of an 8R.