Featured Have you ever wondered what luster looks like?

Discussion in 'US Coins Forum' started by TypeCoin971793, Jan 23, 2019.

  1. I’m not using a biological microscope. It is definitely illuminating what it is magnifying. But it certainly not a professional grade metallurgical microscope
     
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  3. desertgem

    desertgem MODERATOR Senior Errer Collecktor Moderator

    My photos in post #9 were in a thread where comparing the toning differences between Morgan and Peace dollars and Doug and others mentioning the saw tooth ridges ( seen horiizontal angle) were different and the Peace being shorter not as much toning aspect. Jim
     
  4. GDJMSP

    GDJMSP Numismatist Moderator

    And that's kind of the key point to it all. It is the difference(s) in the height, width, and uniformity of the ridges that defines what we see, and or don't see when we look at the luster of a given coin. And it is those same qualities of the ridges that also helps to define how the various types of luster tone. In other words, it's the different types of luster that explain to a large degree why different types of coins tone differently than one another. Even when they are exposed to the very same environment.

    And before somebody else brings it up, I will. Die wear, and the lines seen on coins caused by wear due to metal flow, does not increase luster, it decreases luster. This is because the wear lines in the dies caused by excessive metal flow produce lines of various sizes, some larger some smaller, and this decrease in uniformity of the ridges decreases the luster.

    We have to remember that the luster we see is a function of the reflection and refraction of light. And the thing that produces the highest quality of luster is the uniformity of the ridges because then they all reflect and refract the light in the same way. Break up that pattern and make it less uniform and naturally you have a lower quality of luster.
     
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  5. Cheech9712

    Cheech9712 Every thing is a guess

    Can you see that in pictures or just coins in hand. Great job. Explained well. Will help many
     
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  6. Cheech9712

    Cheech9712 Every thing is a guess

    Yeah. The E thing was great. @TypeCoin971793
     
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  7. Cheech9712

    Cheech9712 Every thing is a guess

    Oh goodie. Can't wait. Thanks so much. I want to see satin
     
  8. Cheech9712

    Cheech9712 Every thing is a guess

    @TypeCoin971793. Thanks for thinking of us bottom feeders who are in dire help in these areas. Doug
     
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  9. Cheech9712

    Cheech9712 Every thing is a guess

    Damn good job. Now i understand luster. I think
     
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  10. Insider

    Insider Talent on loan from...

    Cheech9712, posted: "Damn good job. Now i understand luster. I think."

    OK, let's give you a test and see. Is there any luster in this image?


    IMG_7847.JPG



    A. Yes, it is reflecting off the plastic but it is not Mint luster.

    B. No, absolutely not!

    What's the correct answer, A or B?
     
  11. physics-fan3.14

    physics-fan3.14 You got any more of them.... prooflikes?

    Insider, the answer to your question is C: all of the above and none of the above.

    You're making a big deal out of the word "luster" - but you of all people should know that when numismatists use the word luster, there is a very specific meaning attached to it. Sure, there might be 8 different definitions in your massive dictionary, but there is a 9th for coins that your dictionary likely doesn't have.

    In that there is light reflected from the surface of the coin, you could say that the coin is exhibiting a type of luster. This is most closely associated with the mineralogical use of the term:

    However, the term has traditionally been applied differently in numismatics. I'm not sure why you are making a big deal out of this, or what point you are even trying to make. Different words have specific meaning in different fields - luster in numismatics means that mint bloom you see on Uncirculated coins, and which slowly gets worn away during circulation. In the traditional numismatic use of the term, then, the coin you posted exhibits no luster. If you are trying to use another definition of the term, then you could argue that it does have luster.

    But we're talking about coins here, and we must use the recognized numismatic definitions of the words. It seems like the second or third time in the past couple of months I've had to make this same point. Different words mean different things in different contexts.
     
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  12. RonSanderson

    RonSanderson Supporter! Supporter

    And when I first collected in the 1960s, the term "patina" was used, but no longer.
     
  13. RonSanderson

    RonSanderson Supporter! Supporter

    I don't want to hijack the thread, but I have just received a very satiny 1941-S that seems a natural for this thread. @TypeCoin971793, would you mind if I contributed a couple of photos? (Which I will be taking shortly...)
     
  14. Insider

    Insider Talent on loan from...

    physics-fan3.14, posted: "Insider, the answer to your question is C: all of the above and none of the above.

    You're making a big deal out of the word "luster" - but you of all people should know that when numismatists use the word luster, there is a very specific meaning attached to it. Sure, there might be 8 different definitions in your massive dictionary, but there is a 9th for coins that your dictionary likely doesn't have.

    In that there is light reflected from the surface of the coin, you could say that the coin is exhibiting a type of luster. This is most closely associated with the mineralogical use of the term:

    [Well stated, see we agree. You just made my case, as I'm a geologist by training and many of the terms I brought over to the Certification Service and ANA Seminars in the 70's came from that field.]

    However, the term has traditionally been applied differently in numismatics. I'm not sure why you are making a big deal out of this, or what point you are even trying to make. Different words have specific meaning in different fields - luster in numismatics means that mint bloom you see on Uncirculated coins, and which slowly gets worn away during circulation. In the traditional numismatic use of the term, then, the coin you posted exhibits no luster. If you are trying to use another definition of the term, then you could argue that it does have luster.

    But we're talking about coins here, and we must use the recognized numismatic definitions of the words. It seems like the second or third time in the past couple of months I've had to make this same point. Different words mean different things in different contexts."

    :rolleyes: You wrote a book that reads like you were taking copious notes in one of my classes. :jawdrop::facepalm: That's why I recommend folks get a copy as there is very little I would correct. That fact alone proves how far the hobby has evolved. ;)

    However, I'm sorry to disagree (YOU FLUNKED THE TEST) with you, but before you became a numismatist I was applying the word "luster" in all it's uses as I learned from folks from the mint.


    You may be interested to learn that the fact that a coin's MINT LUSTER came from die erosion was virtually unknown to most (over 98%) professional numismatists when I started my career! No one differentiated between the different types of luster either. Thankfully, there is enough "old knowledge" and "new knowledge" today that a person can practically be self taught in a short period of time if they apply themselves.


    Now, I'm pretty sure you have helped many people learn about MINT Luster as you wish to confine it. I have too. However, as I posted above, I have found that the fastest way to get ANYONE who knows nothing about coins to learn what Mint Luster is as we apply it to coins is to keep it simple and first teach them what "luster" (like that coming off the light reflecting from my black plastic keyboard) actually is. Once they understand what to look for and can see the reflected "luster" from my greasy o_O :vomit: forehead in front of the class, they can look at a coin and see it on an uncirculated coin all the way down the grading scale. Then they learn that all "luster" from a coin is not original as a heavily polished coin has so much luster that it can blind them.

    I'm here passing on opinionated information. Much of it the advanced numismatists as yourself already know. Hopefully, some of my rants will be helpful at guiding others up to your level.

    PS I look forward to future corrections from you as this is how everyone learns. Then, they can choose as they please.:D
     
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  15. Insider

    Insider Talent on loan from...

    If you collected ancient, you would know that "patina" has been used to describe coins before either of us was born. Check out some old books and auction catalogues.

    PS Put "patina" in the search box here.
     
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  16. RonSanderson

    RonSanderson Supporter! Supporter

    OK, that convinces me to post my pictures whether I am welcome or not! But this satiny coin has a much different type of luster so I would like to l learn what people know about it. (I posted a very shiny dime yesterday as post #23601.) There is plenty of detail of die erosion (or, maybe, it's whizzing), but it's manifesting itself as a very intriguing finish.

    This animation does not support full color fidelity, being limited to 256 colors on each of the 9 frames, but it should give a feel for the satiny finish. There is nothing shiny about this dime.

    10c 1941-S full 01.gif

    Now, for full-scale crops at my setup's limit of resolution.

    Two from the obverse.
    upload_2019-1-28_19-4-27.png

    upload_2019-1-28_19-4-38.png


    And two from the reverse. If you look at the plateau of the star you can see how clear it is.
    upload_2019-1-28_19-4-48.png


    upload_2019-1-28_19-4-56.png

    Edit: I accidentally captured my mouse cursor in some of the images. It’s like Where’s Waldo if you’ve a mind to search for them.
     
    Last edited: Jan 28, 2019
  17. physics-fan3.14

    physics-fan3.14 You got any more of them.... prooflikes?

    Thanks for that explanation, @Insider . I see why you're making the points that you are - I think we just disagree on the best technique for explaining the effects (your earlier posts in this thread weren't the most clear to me, but thanks for the explanation).

    The fact that the same word is used to describe two different things isn't really helping anyone.... but at least we cleared up the fact that we're talking about two different things now.
     
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  18. Pretty coin with nice natural luster. :)
     
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  19. physics-fan3.14

    physics-fan3.14 You got any more of them.... prooflikes?

    What we term "mint luster" is actually more accurately related to "chatoyancy." That would clear up the confusion with two meanings for one word.

    But I don't see that term catching on in numismatics, as we are far too traditional.
     
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  20. iPen

    iPen Well-Known Member

    Isn't this sunburst dial a macro version of luster on business strike coins?

    Pic from the 'net.

    [​IMG]
     
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  21. GDJMSP

    GDJMSP Numismatist Moderator

    I think to really make sense of this we have to look at pictures of both the coins involved side by side. So here's the one in this thread - call it A

    [​IMG]

    And here's the one from the other thread - call it B

    [​IMG]


    The simple answer, the luster of A has a more satiny appearance than B because the luster on A is somewhat subdued.

    So why is the luster more subdued on A ? From what I can see it's because A has a weaker strike than B, and that much at least is partially explained because A was struck with misaligned dies, evidence of which is plainly seen on the rims of A on both the obv and rev. And, a strike with misaligned dies means the coin was struck with less pressure, and that results in less, or subdued luster.
     
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