US Coins

Reverse Proof American Buffalo in production: West Point Mint saves 'first strike' American Buffalo

At 8:45 a.m. Eastern Daylight Time June 4, the first Reverse Proof 2013-W American Buffalo $50 gold coin was struck at the West Point Mint, inaugurating full-scale production for an issue to be offered by the U.S. Mint later this year.

After the 1-ounce .9999 fine gold coin was struck, it was placed inside a special envelope on which was recorded the date, time and shift of production, serial numbers of the obverse and reverse dies used, and identification of the specific Gräbener coinage press on which the coin was struck.

The enveloped coin was then secured inside a vault to preserve the historical record for the issue.

The obverse and reverse dies on the Gräbener GMP 360 coinage press used to produce the Reverse Proof coins are oriented to strike with a vertical motion. The upper or hammer die bears the American Buffalo coin’s obverse image, while the lower or anvil die carries the reverse design.

A press operator feeds the planchets between the coinage dies one at a time by hand, using dedicated tongs.

Each coin is struck three times between the dies, with each strike of the dies exerting 120 tons of pressure, to ensure the planchet’s metal completely fills the design elements in the obverse and reverse dies. The outward expansion of the coin is restrained by a reeded edge collar die, which imparts the reeded edge.

After the three designated strikes, the collar retracts and the struck coin rests on top of the anvil die until it can be safely removed with tongs.

Each struck coin is individually inspected, with or without magnification as the press operator deems necessary. The operator looks for defects that would result in the coin being rejected, such as scratches or other similar damage.

Struck coins may also be rejected at subsequent inspection and quality control stations.

Approved examples move on to the encapsulation station, where the coins are placed into plastic capsules and then inserted into the final packaging.

Stern-Leach, of Attleboro, Mass., currently fabricates the blanks used for American Eagle and American Buffalo coins from gold the U.S. Mint secures on the open market from a number of gold suppliers, including Metalor, Johnson Matthey, Ohio Precious Metals and the Royal Canadian Mint.

Since production of the Reverse Proof coins only began June 4, Mint officials have no production statistics yet on die life or rejection rates.

The finish on the Reverse Proof coin is the opposite of that for a regular Proof. On a regular Proof coin, the devices and lettering are frosted against mirrored, polished fields. On the Reverse Proof, the devices and lettering elements are polished to a mirrored finish, on frosted fields. ¦

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