On January 24, 1848, James Wilson Marshall noticed some small flakes of yellow metal near the Sutter's Mill project outside Coloma, California. Marshall's discovery turned out to be gold, touching off one of the largest voluntary migration of humans the world has ever known -- the California Gold Rush.
In December 1848, the Military Governor of California, Col. R.B. Mason, sent 228 ounces of newly mined gold to the Secretary of War, William L. Marcy. Marcy forwarded the gold to the Philadelphia Mint, with instructions to use the gold for Congressional Medals for Generals Zachary Taylor and Winfield Scott. Any leftover gold was to be turned into specially marked Quarter Eagles. 1,389 1848-dated Quarter Eagles were struck from the California gold shipment, each one stamped with a small "CAL." in the upper reverse field. The stamping appears to have been done while the coins were still in the press, as none of the obverse features appear to have been flattened. At least one example (the James F. Lindsay - 1978 GENA, Lot 1839 example) shows triple punching.
Beware of forgeries with fake "CAL." punched into regular 1848 Quarter Eagles. This normally results in some flattening of the obverse features opposite the punch. We're not aware of any metallurgical testing having been performed on the various 1848 Quarter Eagles, but we suspect that the California ore of the "CAL."s will contain trace elements in different amounts than in the "Eastern" ore of the regular 1848 Quarter Eagles. Only a single "CAL." punch was used, so any pretender must match the exact positioning and spacing of the lettering and period of the punch on a known genuine piece (see enlarged image above). Placement of the punch relative to other elements on the reverse varies, so this cannot be used as an indicator of authenticity.
Some 1848 "CAL." Quarter Eagles have been called "Proof" in the past (Delp, Miles, Pierce, and Kern), but none were struck from the same dies as true 1848 Proofs.
Sources and/or recommended reading:
"Walter Breen's Complete Encyclopedia of U.S. and Colonial Coins" by Walter Breen
"The PCGS Population Report, April 2003" by The Professional Coin Grading Service
"United States Gold Coins - An Analysis of Auction Records, Volume II, Quarter Eagles 1796-1929" by David W. Akers