The early 20th century was a golden age of U.S. coin designs including such depictions as an Indian and bison on the 5-cent coin, a depiction of Liberty wearing a winged cap on the dime and an image of a Walking Liberty on the half dollar.

Perhaps the most memorable of these classic early 20th century designs is the contribution made by the famed sculptor Augustus Saint-Gaudens, who created the $20 double eagle of 1907 to 1933 that today bears his name. Saint-Gaudens died in 1907. The lower relief variety of his coin struck later in that year and throughout the rest of the series was actually prepared by U.S. Chief Mint Engraver Charles E. Barber.

Saint-Gaudens’ participation in coinage designs dated from 1891, when he first sat on a committee reviewing designs for silver coins. He became upset with government officials a few years later when they rejected the reverse design for his World’s Columbian Exposition commemorative presentation medal, as well as rejecting several revised designs.

Saint-Gaudens' creation of designs for the $10 eagle and $20 double eagle was at the behest of President Theodore Roosevelt. Both men wished to see a higher quality of U.S. coinage designs.

The solicitation of an "outside" sculptor did not sit well with the Mint's sculptor- engraving staff, including Barber. At one point during the designing process, Saint-Gaudens wrote to Roosevelt and said, "If you succeed in getting the best of the polite Mr. Barber ... or the others in charge, you will have done a greater work than putting through the Panama Canal."

Saint-Gaudens' original version of the coin struck for circulation has higher relief than was practical. Barber created a lower relief version to replace Saint-Gaudens' original concept. Saint-Gaudens, who had been ill with cancer while designing the coin, died before any $20 patterns or coins bearing either his original or modified designs were struck.

Several major versions of the coin may be included in a type collection: the Extremely High Relief, Roman Numerals, Lettered Edge coin of 1907; the High Relief, Roman Numerals, Wire Rim coin, also 1907; the High Relief, Roman Numerals, Flat Rim coin, 1907; the Arabic Numerals, Low Relief, No Motto coin, 1907 and 1908; and the Arabic Numerals, Low Relief, Motto coin, 1908 to 1933.

All High Relief coins struck during 1907 met with objections from bankers, who said the coins could not be stacked. There are arguments regarding how many of some of these coins exist, with new "discovery" pieces periodically appearing in the market.

The value of the High Relief coins puts most of them virtually out of reach of the average collector. There are sufficient expensive key dates in the series that few collectors have been able to assemble a collection complete through 1932.

According to Mint records 445,000 Saint-Gaudens double eagles were struck in early 1933. The government contends the coins were never officially released into circulation because of President Franklin D. Roosevelt's executive order halting the circulation of all gold coins in March of 1933 was issued before any of the coins could be released. However, research in 2010 by numismatist Roger W. Burdette uncovered Mint documentation indicating that the first striking of 1933 double eagles occurred March 2, 1933, before the national bank holiday and Roosevelt’s initial call for citizens to turn in gold.

The 1933 double eagles were ordered to be melted in 1937 and for years government officials believed all had been destroyed. However, in the early 1940s examples began to appear in the numismatic marketplace. The government confiscated at least nine examples in the 1940s and destroyed them.

In 1996 government agents seized another 1933 double eagle from a British coin dealer entering the United States. The coin was claimed by some to be the 1933 double eagle once owned by Egyptian King Farouk, who was granted an export license for the coin by the Treasury Department in 1944. The coin became the subject of a prolonged court battle and in an unprecedented action, United States Mint officials reached an out-out-court agreement with the British coin dealer to permit the seized coin to be sold at public auction and the proceeds to be split evenly between the dealer and the Mint.

The 1933 Saint-Gaudens double eagle was sold July 30, 2002, in New York City in a one-lot auction conducted by Sotheby's in conjunction with Stack's for $7.59 million plus $20. It is the only 1933 double eagle approved by the Treasury Department for private ownership.

Another 10 1933 double eagles turned up in 2003 when Joan Switt Langbord, daughter of Philadelphia jeweler Israel "Izzy" Switt, claimed she found them in a family safe deposit bank box. Izzy Switt was the dealer who initially sold the 1933 coins that surfaced in the 1930s and 1940s. He died in 1990 at age 95.

Langbord and her two sons, Roy Langbord and David Langbord (Israel Switts' heirs), asked the U.S. Mint to determine if the coins she found were genuine. Treasury agents declared the coins to be genuine and also confiscated them in 2004. The Langbord family filed suit seeking return of the coins and the case was still in litigation in 2010.

Some researchers believe that Burdette's research, including uncovering Mint documents indicating the first 1933 double eagles were struck before Roosevelt’s gold recall, shows that some of the coins could have left the Mint legally, thus legitimizing them.

Mintages were never very high on any Saint-Gaudens double eagles. The highest mintages recorded are 8,816,000 for 1928; 4,323,500 for 1924; and 4,271,551 for the 1908 No Motto.

The high mintage of the 1908 No Motto coin makes it attractive as a type coin alongside a subtype with the motto IN GOD WE TRUST. According to David Akers in United States Gold Coins, An Analysis of Auction Records, Volume VI, "A great many Uncs of this date exist, literally thousands of pieces, and the collector will encounter no difficulty in locating a choice or gem quality example."

This two-coin variety set should be affordable, where date collecting of this series may not be.

A type set including Roman numeral dates and High Relief coins will be more expensive to complete.

A type set of coins by Mint in both Motto and No Motto varieties is also possible at a modest price. Mint marks are on the obverse for the Saint-Gaudens series, an unusual placement for Mint marks on U.S. coins from this period.

Disregarding 1933 coin and the pricy 1907 varieties, collectors seeking this series must still contend with such low mintage key dates as 1913-S (34,000 mintage), 1914 (95,230 mintage), 1915 (152,050 mintage), 1930-S (74,000 mintage) and 1931-D (106,500 mintage).

Although perhaps not reflected in their mintage figures, the 1931 and 1932 coins are also difficult dates to obtain.

Another popular coin in the series is the 1909/8 overdate. Akers notes, "It is not a particularly rare one," but the clear overdate makes the coin attractive to collectors.

Proof coins exist for all dates between 1907 and 1915. As with most Proof coins in this time period, they were struck in extremely low quantities and can be quite expensive. The highest mintage is a mere 167 pieces dated 1910. The survival rate of this date in Proof is significantly lower.