Authentication Guide: 1857-S SS Central America $20 Gold Coin

Historical Significance

The 1857-S SS Central America $20 gold coin is one of the most significant shipwreck discoveries in numismatic history. The SS Central America, known as the “Ship of Gold,” sank off the coast of South Carolina in September 1857 during a hurricane, carrying approximately 30,000 pounds of gold from the California Gold Rush. Discovered in 1988 by the Columbus-America Discovery Group, the recovery of its treasure revolutionized the coin collecting market.

These coins were minted in San Francisco and were part of the cargo destined for Eastern banks. The 1857-S issue is particularly significant because it represents the last year of production before the shipwreck. Coins from this hoard were preserved in near-perfect condition due to the protective environment of the ocean floor, making them highly desirable to collectors and investors alike.

Identifying Key Markers

Weight and Dimensions

Authentic 1857-S SS Central America $20 gold coins should weigh precisely 33.436 grams (approximately 1.075 troy ounces). The diameter measures 34mm with a thickness of 2.03mm. Any deviation from these specifications should raise immediate concerns about authenticity.

Metal Composition

These coins are composed of 90% gold and 10% copper alloy. The gold content should test at 21.6 karats. The specific gravity should measure between 17.3 and 17.5, consistent with the gold-copper alloy composition.

Die Markers and Design Features

Key diagnostic features include:

• Liberty’s coronet should show crisp detail with the letters “LIBERTY” clearly visible across the headband
• The date “1857” should be sharply struck with no signs of tooling or alteration
• The “S” mint mark below the eagle’s tail feathers should be well-defined
• Reverse stars should show full radial lines extending to the edges
• The shield on the reverse should display complete horizontal and vertical lines

Surface Characteristics

SS Central America coins often display unique surface features from their time underwater:

• Slight granularity or “ocean etching” on the surfaces
• Consistent toning patterns across the coin
• Minimal contact marks due to protective encasement in sediment
• Occasionally, small marine deposits may be present in protected areas

Common Fakes and Counterfeits

Cast Counterfeits

The most common fakes are cast copies made from original coins. These can be identified by:

• Loss of fine detail, especially in Liberty’s hair and the eagle’s feathers
• Pitting or porosity on the surface
• Incorrect weight (typically 10-15% lighter than authentic specimens)
• Soft, rounded edges rather than sharp, squared rims

Altered Date Fakes

Scammers may alter dates on common-date $20 gold pieces to resemble the valuable 1857-S. Look for:

• Inconsistent patina between the date and surrounding areas
• Tool marks or evidence of date manipulation
• Incorrect die characteristics for 1857-S issues
• Discrepancies in the spacing of numerals

Modern Replicas

Tourist-grade replicas are often sold as “shipwreck coins” but lack proper authentication. These typically feature:

• Incorrect metal composition (often brass or gold-plated base metal)
• Missing or incorrect mint marks
• Modern proof-like surfaces inconsistent with shipwreck preservation
• Absence of proper documentation and certification

Testing Methods

Magnetic Testing

Authentic gold coins are non-magnetic. Use a strong neodymium magnet to test the coin. If the coin exhibits any magnetic attraction, it is definitely counterfeit. However, the absence of magnetism alone does not guarantee authenticity, as some sophisticated counterfeits use non-magnetic metals.

Specific Gravity Test

This test provides excellent results for authentication:

1. Weigh the coin in air using a precision scale (accurate to 0.001 grams)
2. Weigh the coin suspended in water using a specialized setup
3. Calculate specific gravity using the formula: SG = Weight in Air / (Weight in Air – Weight in Water)
4. Authentic coins should yield a specific gravity between 17.3 and 17.5

Visual Inspection Under Magnification

Examine the coin under 10x to 20x magnification:

• Check for proper strike characteristics and die polish lines
• Look for signs of casting such as bubbles or surface irregularities
• Examine the edge for proper reeding and any signs of casting seams
• Verify the consistency of the mint luster and surface texture

Professional Authentication

For high-value specimens, professional authentication is essential:

• PCGS and NGC provide certified encapsulation with detailed attribution
• ANACS offers authentication services with detailed grading reports
• Independent experts can provide second opinions on questionable specimens

Documentation and Provenance

Authentic SS Central America coins should come with comprehensive documentation:

• Original recovery documentation from the Columbus-America Discovery Group
• Professional grading and certification from reputable services
• Chain of custody records tracing the coin’s history
• Photographic documentation of the coin before encapsulation

The Manchester show report mentioned in the forum discussion highlights the importance of examining these coins in person. The attendee who acquired the 1857-S MS63 PCGS coin from the shipwreck gold specialist demonstrates the value of attending specialized shows where authentic specimens are available for direct examination.

Market Considerations

The market for SS Central America coins remains strong due to their historical significance and limited supply. Premiums over standard 1857-S issues can range from 50% to 200% depending on condition and certification. The MS63 grade mentioned in the forum represents a high-end specimen that would command significant value in today’s market.

Collectors should be particularly cautious when purchasing from online sources or dealers who cannot provide proper documentation. The forum discussion about the $50 Humbert slug illustrates the importance of verifying authenticity through multiple channels and consulting with experts before making significant purchases.

Conclusion

The 1857-S SS Central America $20 gold coin represents a unique opportunity to own a piece of American history. However, the high value of these coins makes them prime targets for counterfeiters. By understanding the specific diagnostic points outlined in this guide – including weight, magnetic properties, die markers, and proper testing methods – collectors can protect themselves from fraudulent specimens.

Remember that authentication is a multi-faceted process. No single test is definitive, and the most reliable authentication comes from combining multiple testing methods with professional certification. When in doubt, consult with experienced numismatists or send the coin to a reputable grading service for expert analysis.

The excitement expressed by the Manchester show attendees about their shipwreck gold discoveries underscores the enduring appeal of these coins. With proper knowledge and authentication techniques, collectors can confidently pursue these remarkable pieces of American numismatic heritage.

Related Resources

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