Some comments about natural luster
RWB
Posts: 8,082 ✭
This was embedded in another post, but it might be of interest to others. In general this applies to production coins from about 1850 to 1970. (Exceptions mostly occur in Morgan dollars where some dies were rebasined before initial use.)
The reasons finding well struck 1921 [Peace dollars] that also have appealing luster relate to die life and the origin of luster.
New dies had a smooth, satin-like surface. As they were used, metal flow in the dies created the fine lines collectors identify as luster. In extreme cases, metal flow became so severe that prominent lines radiating from the center of the die became evident. This effect is called “starburst.” Thus, appealing luster is an attribute of dies that have been in use for several hundred (or thousand) coins or more.
1921 dies were in high relief and it required all the pressure a production press could apply to strike a coin with most of the design detail evident. But doing this created excess stress on the dies and resulted in early die failure – early enough that die luster only partially developed.
By reducing striking pressure, die life was extended, but at the cost of poor high point detail. These coins invariably have nice luster but insufficient central design detail.
Assuming an unaltered specimen, coins exhibiting attractive luster generally were made from mid- to later-life dies. New dies produced coins with limited luster, but had the potential for maximum detail. (Buffalo nickels, SL quarters, WL halves, 1921 Peace dollars are prime examples.)
The reasons finding well struck 1921 [Peace dollars] that also have appealing luster relate to die life and the origin of luster.
New dies had a smooth, satin-like surface. As they were used, metal flow in the dies created the fine lines collectors identify as luster. In extreme cases, metal flow became so severe that prominent lines radiating from the center of the die became evident. This effect is called “starburst.” Thus, appealing luster is an attribute of dies that have been in use for several hundred (or thousand) coins or more.
1921 dies were in high relief and it required all the pressure a production press could apply to strike a coin with most of the design detail evident. But doing this created excess stress on the dies and resulted in early die failure – early enough that die luster only partially developed.
By reducing striking pressure, die life was extended, but at the cost of poor high point detail. These coins invariably have nice luster but insufficient central design detail.
Assuming an unaltered specimen, coins exhibiting attractive luster generally were made from mid- to later-life dies. New dies produced coins with limited luster, but had the potential for maximum detail. (Buffalo nickels, SL quarters, WL halves, 1921 Peace dollars are prime examples.)
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Comments
Greg
I believe this explains, in part, why it is so difficult to find truly lustrous Shield Nickels. The dies for Shields tended to break before they had a chance to develop the flow lines that cause the quality of coruscation that we call "cartwheel" luster on coins. Henry Linderman, during his first of two stints as Director of the Mint, complained in his first annual report (1867) that the nickel panchets “had worn out the Mint’s machinery and broken an enormous number of dies.” D. Taxay, The U.S. Mint and Coinage at 246 (1966). “Because of the hardness of the coinage metal, the limits on the diameter of the coin and technology of the period, the [Shield Nickel] dies lasted for only 10,000 to 15,000 coins per die pair.” E. Fletcher, The Shield Five Cent Series at 16 (1994). Noted numismatic researcher Bob Julian has conducted extensive research of relevant documents at the National Archives and “reports that ‘the average number of 5-cent coins from each pair of dies was well under 15,000.’” G. Peters & C. Mohon, The Complete Guide to Shield & Liberty Head Nickels at 4 (1993) (quoting R.W. Julian). QDB also relies upon Julian’s research in writing that “somewhat fewer than 20,000 impressions for the 1866 and 1867 With Rays type improving to about 20,000 to 21,000 for the Without Rays nickels of the earlier years, and rising to about 26,000 by 1882.” Q.D. Bowers, A Guide Book of Shield and Liberty Nickels at 72 & n.19 (citing personal communication with Julian in June 2005).
RWB...ever notice that some super lusterous 1921 peace dollars tend to have semi circular flow lines?
Eduted to add: I meant to say semi circular die polish lines, not semi circular flow lines.
<< <i>Astute collectors can use this information to help them buy superior coins at similar cost as ordinary pieces. >>
or is that combination rare?
As others said, this is valuable information -- thanks. Did you source this information from somewhere specifically or is it just accumulated knowledge?
"Look up, old boy, and see what you get." -William Bonney.
The key part is distilling everything into a few lines that provide a high-level, simple description that doesn’t take too much background knowledge to understand. (If you add the details, you could end up with a small book.)
This does not explain the halo affect I've seen on many mint state coins where their is a ring around the portraight with no luster. This does explain the prooflike & semi prooflike intense cartwheel effect but it doesn't explain luster breaks to the left of the portraight on bust coins or to the right of the portraight on seated or barber coins.