So I know that die polish is generally a sign that a coin is genuine. And I also know its often found in protected areas, such as the date, on certain devices, and crevices. Sometimes I've heard it is swirly, other times I have seen it straight. But they do appear to be finer, thinner than tool marks. The reason I ask this is I took out my $5 PCGS AU58 indian head eagle for examination. I notice what appears in the neck of the indian to be fine die polish lines, also right below the neck band. It is obviously genuine since both ANACS (the old ANACS in the small holder), and PCGS slabbed it. Am I correct on this assumption to tell the difference between the two? My other question is, what exactly causes spikes from the denticals? I seem to remember somewhere it was from a certain die making process (EDM?), perhaps from spark erosion dies? And I encourage other people to post in this thread to post any questions they have on authentication in general, including alterations. I think Matt's Thread is a real eye opener on the subject and I think we all need to ask more questions, and I think that's a great way to learn, as well as looking at many genuine coins, understanding how counterfeit coins are made, knowing what genuine coins look like, understanding how genuine coins are made, and understanding the diagnoses of counterfeit coins. Here is the photo I took of the coin a couple years ago, and I think what's shown here is die flow lines (not die polish lines):
In the photos, it APPEARS to me that the upper photo shows die polish, the lines appear to be raised and on the flat surfaces of the coin. The second photo looks more like metal flow lines to me. Since polishing was usually carried out on the flat surfaces of the dies, the devices should not have polishing marks. However, on the $2.50 and $5 Indians, with the portrait being incuse into the coin, I wonder if that part of the die would be more susceptible to acquiring polish marks, unless great care was taken during the process. I'm no expert on these coins, for sure.
Thanks, I figured the top photo had die polish because the die polish seemed to travel from the raised areas of the coin (the field) to the incuse design. And they seemed finer than tool marks and raised. I talked to Doug in PM about the tool marks/die polish difference and he said that with die polish you often find more than 1 or 2, sometimes a dozen or more at once. Now I'm not sure what I saw was die polish or metal flow, I'm not experienced enough at the moment to tell the difference, but what I did find is that if this is die polish on the neck of the indian, and underneath the neck band then there seems to be alot of it. Not just 2 or 3 lines.
To understand die polish lines think about this. All of those little protected areas like inside the letters and numbers or the small flat, low areas on a coin like under the hair at the back of the neck or places like that. Well on a die, all of those places are the high, flat points that stick up in the air. It is these high, flat points that are polished to make them smooth again. So while on a coin these points are the hardest to get to, on a die they are the easiest to get to because they stick up in the air all by themselves. You put a little diamond paste on your polishing belt and just hold the die down against it. Voila - the die is polished. Now on the incuse Indian designs all of this is in complete reverse. And polishing those dies after use, that took some work. And precision work at that.
Ahh, I see. What about if you had a counterfeit coin with depressions on it? Those are contact's on the genuine coin, which gets transferred to the die (As raised lumps?) then the coin gets struck and these marks appear on the coin/planchet as 'depressions', soft rounded, luster filled crevices. I hope this is right! Sorry doug, I have a really hard time learning things. But I appreciate your patience with me.
You've got it Kevin. What helps a lot of people to understand stuff like this for them to sit down and draw pictures. No need for them to be accurate in regard to design. Just draw simple pictures. When a die starts out, the end of it is a flat piece of metal. When pressed into a hub, the design becomes incuse, sunken down into that metal. Everything else remains flat and in the same place it was. With coins it's the reverse. The planchet is basically flat. then when struck, parts of that planchet raise up and the rest remains flat. Now you draw pictures of that stuff at the different stages and it all begins to make sense.
Definitely, I need to find some pictures, I need to see them to understand it fully. I have trouble reading books (especially numismatic forgery) and understanding what's what without pictures or video.
You don't need to find any, just sit down and draw them yourself. Just draw a stright line to indicate the flat die. Then dip another line down under it in an arc to simulate the incuse devices. Then do the reverse of that for the coin. You're not trying to draw actual renditons of the coin, just the effects.
Beginning to make sense now. So basically for early die varietes, such as the 1836 $2.50 classic head. You have blank soft die, it is placed into a hub which gives it the design. The designs are incuse into the die. The flat parts of the die where the polish is where the the recessed areas are in the case of an incuse design coin. Then, before the coin is struck, certain details are hand punched into the die with punches, some slightly different on some dies, creating die varieties. I still need to draw pictures to figure out how this would look on an incuse design, versus a regular relief coin.
