Coronet gold $20 double eagles, also known in as the "Liberty" $20, have seen the most dramatic trading action so far this year in the entire coin market.

The "better dates," which are scarcer than the most common issues, and the ultra rarities in this series began the year with strong price increases at the major auctions surrounding the Florida United Numismatists convention. Then a week later in New York City, Stack's held an auction featuring a virtually complete collection of circulated, Mint State and Proof Coronet double eagles.

Prices in the Stack's auction soared even higher than the previous week's round of auctions for these coins.

In traditional Stack's style these coins were "raw" – ungraded and unslabbed by third-party grading services. Even though many buyers agreed with the grades assigned the coins by Stack's catalogers, there was some room left for interpretation by buyers as to whether some coins would upgrade after being submitted for grading or remain about the same as what the catalog listed.

Coronet double eagles have been strong throughout this five-year-old bull market, but the series did take a breather, with a little softening in values roughly a year ago. But now demand is back with a vengeance.

Following are some examples from these sales: 1855-O Numismatic Guaranty Corp. About Uncirculated 55, $51,750; 1857-O NGC AU-58, $23,000; 1858-O NGC AU-55, $20,700; 1861-S Paquet Reverse NGC AU-58, $161,000; 1866-S No Motto Professional Coin Grading Service Extremely Fine 45, $19,550; 1866-S No Motto PCGS EF-45, $28,750; 1869 PCGS Mint State 65, $299,000; 1870-CC EF-40, $253,000; 1871-CC EF-45, $34,500; 1872-CC MS-60, $40,250; 1879-O EF-45, $37,375; 1881 AU-50, $17,825; 1885 AU-55, $40,250; 1886 AU-50, $63,250; 1891 MS-62, $115,000.

Each coin rides on its own merits – notice the $9,200 difference between the two 1866-S No Motto coins graded the same (EF-45) by two different services. Most of these coins at auction are purchased by dealers, so there is a profit margin reflected in the published values. Coin Values updates are based primarily on auction results and reflect retail prices that a buyer would pay.