Unscrupulous sellers knowing the value of naturally toned coins sometimes swap out those gems and replace them with the same year/mint examples of lesser value. Usually you can tell what sets have been tampered with, either because of the stark toning contrast or wrong packaging, as in these examples:
The best way to check if your set contains the wrong boards is to go to the APMEX coin site and see the distinct packaging, whose paper or cardboard are responsible for specific toning patterns, sometimes unique to the impurities of the planchets of a particular year.
Of all the years, the high mintage 1958 Double Mint Set is among the most desirable because of the stunning natural toning, especially the Denver silver coins that have distinct rainbows with these shades of red, blue, green, gold, yellow and magenta:
The 1958 Philadelphia coins often have a purple/blue/magenta/amber toning, as in this example:
So when I see an eBay set with artificial coloring, like the one below, I know immediately not to buy, bid or otherwise inquire about the double mint set. Can you spot the chemically treated coins?
Let’s take a closer look:
Another red flag are partial sets. You have to know the mintages. Some sets feature 18 coins (1956), and others 22 coins (1955), 28 coins (1947-49) and 30 coins (1951-1954, 1957-58).
A few years ago you could find original toning in the 1958 and other double mint sets containing these mintages:
- 1947 (5,000)
- 1948 (60,00
- 1949 (5,000)
- No 1950
- 1951 (8,654)
- 1952 (11,499)
- 1953 (15,538)
- 1954 (25,599)
- 1955 (49,656)
- 1956 (45,475)
- 1957 (32,324)
- 1958 (50,314)
Retail prices for the low mintage sets (1947-49, 51-520 can range in the hundreds and thousands, as long as they have not been tampered with or doctored.
But the 1958 set with the largest mintage remains among the most desirable because of the rainbow tones. That is why unopened original sets command high prices, as this example:
In addition to selling and buying coins, APMEX has a useful post about detecting artificial v. natural toning:
- Toning that has bright colors, as you would find in a box of crayons.
- Toning that appears to “float” on the surface, rather than having greater depth.
- The toning that appears yellow-brown or smoky. (This indicates the use of cigar or cigarette smoke, common among artificially toned coins.)
- Toning that occurs over hairline marks.
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