Two different varieties exist of the 500 Unit (or "Quint") 1783 Nova Constellation Pattern coins. Both varieties are represented by unique examples. The first variety (Type 1) is similar in all aspects to the unique 1000 Unit, the three known 100 Units, and the unique 5 Unit. The second variety (Type 2) shares the same reverse (denomination side) with the Type 1 Quint, but has a stylistically different obverse. The all-seeing eye motif is retained, but the Type 2 lacks the NOVA CONSTELLATIO legend and has an additional circle within the beaded border. The diameter is smaller (24 mm versus the 27 mm of the Type 1) and the weight is lower (109.72 grains versus the 133.98 of the Type 1). Though inexplicable, these differences have not affected the market acceptance of the Type 2 Quint. At the Chicago ANA convention in 2011, the Type 2 Quint was offered for sale at $3 million.
Breen lists the pedigree as "Unidentified young NYC collector (1870) - W.P. Brown - S.S. Crosby - Lorin G. Parmelee - S.H. & H. Chapman - J.W. Ellsworth - Knoedler Galleries - Wayte Raymond - J.W. Garrett - Johns Hopkins Univ. (1942-79) - Garrett:621, $55,000 - Walter Perschke."
The Type 2 Quint has a thin planchet crack running from the edge through the I of LIBERTAS, through the wreath and to the U of US. This would account for Breen's note that the coin did not ring (a somewhat crude test for authenticity -- struck coins will ring, while cast coins will not). The coin also has "2 Dec." lightly scratched into the field just above U.S.
Sources and/or recommended reading:
Walter Breen. Walter Breen's Complete Encyclopedia of U.S. and Colonial Coins, 114-115.
The Type II Nova Constellatio silver "500" pattern is unique. Interestingly, at the November, 1979 Garrett auction this coin "only" brought $55,000, about one-third the price garnered by the Type I. It is speculated that this was because the coin is a different design than the other Nova Constellatios and has a "funky" look.