If you have time can you summarize the discussion on coin001. I am at a loss because looking at the NGC photo the marks are hand made and look like scratches which was made to look like frosting. Why this type of coin is even graded is a mystery unless for some reason the die was made this way.
The lines were not hand made on the coin. They are not scratches. The NGC scan exaggerated the lines due the 90 degree lighting to those lines. If anything, they look like die polish lines, RISING above the field. I am attaching the picture of a 1980 1 yuan business strike below.
These polish lines do create a frost-like contrast between the field inside the national emblem and the field outside it. Is this effect intentional or accidental? If accidental resulting from normal die polishing, why was polishing limited to the field inside? Considering similar effects on precious metal coins (frosted field inside the emblem), is it possible that the mints were experimenting with some new technology? If it is intentional, why do these lines also occur on proof coins, like the one in your link, which already have frosting? These are some of the puzzles.