Doug Winter: The following information is from my eBook on Type One Liberty Head Double Eagles at http://doubleeaglebook.com/
The 1856 is the second scarcest Philadelphia double eagle produced during the 1850’s after the 1859. It has a lower survival rate than other comparable double eagles struck during this era and it is a very rare (and still under-recognized) issue in high grades.
STRIKE: This is a reasonably well-struck issue. On the obverse, the hair is well-detailed except for the strands at the top of Liberty’s head which are usually weak. The stars will often show full radial lines while the denticles are sharp. The reverse is also well-struck. Some coins show minor weakness on the denticles, often from 4:00 to 7:00.
SURFACES: The surfaces are often liberally abraded but less so than on the 1855 double eagle. There are a small number of 1856 double eagles that have relatively clean surfaces, and these tend to be very highly valued by specialists.
LUSTER: The luster is similar in quality and texture to other Philadelphia double eagles of this era. Higher grade pieces are frosty with nice rich mint bloom. However, more and more 1856 double eagles are being dipped or cleaned and it is becoming harder to locate examples with original luster.
COLORATION: The natural color seen on higher grade pieces ranges from medium green-gold to lighter orange-gold. Less often, examples are seen in a medium yellow-gold hue. The collector should be able to find an 1856 double eagle with natural color but such coins are becoming harder to find with the passing of each year.
EYE APPEAL: This date is seen with below average to average quality eye appeal. Many are found with good strikes and have decent surfaces, but coins with pleasing natural color are becoming very scarce. A CAC-quality 1856 which is choice and original is worth a strong premium over a typical example.
INTERESTING VARIETIES: All 1856 double eagles have an Upright 5 in the date. There are minor positional varieties but none are of interest.
PROOFS: No Proof 1856 double eagles were struck.
HOARDS: 15 pieces were found on the S.S. Republic including three in Uncirculated. There were only five found on the S.S. Central America. A small number of high-grade pieces with very granular seawater surfaces appeared on the market around thirty-five+ years ago. Their origin is unknown to me.
BUYING TIPS: This date has long been a “sleeper” and it is still my favorite Type One Philadelphia issue in regards to value. $5,000 will buy the savvy collector an above-average 1856, and this represents good value in this high-priced series.
AUCTION RECORD: The current auction record for this date is $41,125, set by a PCGS MS63 which was ex Stacks Bowers 2014 ANA: 12013.
FINEST KNOWN: Two or three exist in MS63, and these are the highest graded 1856 double eagles. The best of these is probably Stacks Bowers 2014 ANA: 12013 ($41,125) which was obtained by the consignor from me in March 2002.
TOTAL KNOWN: 550-650+
Very Fine: 200-250
Extremely Fine: 240-250
About Uncirculated: 95-125
POPULATION FIGURES: As of the beginning of 2015, PCGS had graded two in MS60, 14 in MS61, eight in MS62, and three in MS63 for a total of 27 in Uncirculated. NGC had graded four in MS60, 12 in MS61, three in MS62, and one in MS63 as well as three in MS61 from the S.S. Republic for a total of 23 in Uncirculated. These figures are slightly inflated by resubmissions, especially in MS61 and MS62. CAC has approved one Uncirculated exampled graded MS61.
PERFORMANCE SINCE 2002: In the current market, a choice Extremely Fine example (equivalent to an EF45) is worth $2,250-2,500. In 2002, this coin was essentially regarded as a “generic” Type One and was worth $600-800. In the current market, a choice About Uncirculated example (equivalent to an AU55) is worth $4,000-5,000. In 2002, this coin was worth $2,000-3,000. Given this information, I believe that the 1856 in AU55 remains undervalued.
COMMENTS: The 1856 double eagle is among my favorite Type One double eagles. It is not often seen in properly graded About Uncirculated-55 to About Uncirculated-58, and it remains an excellent value in this range. In Uncirculated, this is a genuinely rare coin and I have seen very few which I graded higher than MS61.
David Akers (1975/88): The 1856 is a very elusive date, generally obtainable only in VF or EF condition. In AU it is very scarce and in unciculated 60 or better it is rare. Locating a choice or gem quality unc would be a very difficult task indeed and I have seen only a couple at those levels. As is the case with a number of the $20 issues from the mid-1850's, particularly the S-Mints, "saltwater uncs" are occasionally available (cf1974 ANA). Among Type I Double Eagles from the Philadelphia Mint, the 1856 is comparable in overall rarity to the 1855, 1857, 1858, 1863 and 1864 although it is a little easier to locate in Unc. than the latter four dates, particularly the 1863 and 1864 which are all but unobtainable in mint state.