1851 $50 Augustus Humbert Slug Value & Price Guide

During the California Gold Rush, there wasn't enough federal coinage to support the booming economy. Miners had gold dust but no way to turn it into money that merchants would accept at standardized values. In 1851, the United States Assay Office in San Francisco, under Assayer Augustus Humbert, began striking massive octagonal $50 gold pieces to solve the problem. Locals called them "slugs" because of their hefty weight: each coin contained nearly 2.5 ounces of gold. They are among the most spectacular pieces of American coinage.

The 1851 Humbert $50 slug is both a historic artifact of the Gold Rush and a substantial chunk of gold. Values start around $25,000 for damaged examples and can exceed $300,000 for high-grade specimens.

Quick Value Summary

Detail	Info
Item	1851 $50 Augustus Humbert Octagonal Slug
Year	1851-1852
Assay Office	United States Assay Office, San Francisco
Composition	.880-.887 fine gold
Weight	~83.5 grams (~2.68 troy ounces gold)
Category	Coins
Damaged/Problems	$25,000 - $50,000
VF (Very Fine)	$60,000 - $120,000
XF (Extremely Fine)	$120,000 - $200,000
AU (About Uncirculated)	$200,000 - $350,000+
Record Sale	$300,000+ (AU condition)
Rarity	Rare (~100-200 known, varies by variety)

The Story

When James Marshall discovered gold at Sutter's Mill in January 1848, it set off the largest mass migration in American history. By 1849, San Francisco had transformed from a sleepy port town into a roaring city of 25,000. But the US Mint was 3,000 miles away in Philadelphia, and there wasn't enough coined money to support commerce.

Private assayers and minters stepped in to fill the gap, but their coins had inconsistent gold content. The federal government responded by establishing the United States Assay Office of Gold in San Francisco in 1850, appointing Augustus Humbert as the US Assayer of Gold.

Humbert's office began striking $50 octagonal coins in 1851. The obverse featured a federal eagle surrounded by the text "UNITED STATES OF AMERICA" and "FIFTY DOLLS." The reverse showed the stamp of the Assay Office, Humbert's name, and the gold fineness. The octagonal shape distinguished them from regular federal coinage.

These were working money. They circulated in San Francisco's banks, merchant houses, and mining camps. The gold content was reliable, which made them preferred over private mint coins. But their large size and high denomination meant they wore quickly and many were eventually melted when the San Francisco Mint opened in 1854.

How to Identify It

Shape: Octagonal (eight-sided), approximately 41mm across. This unique shape is immediately recognizable.

Obverse: Federal eagle design with "UNITED STATES OF AMERICA" and "FIFTY DOLLS." Some varieties show "50" instead of "FIFTY DOLLS."

Reverse: "AUGUSTUS HUMBERT UNITED STATES ASSAYER OF GOLD CALIFORNIA 1851" with the fineness and target weight.

Edge: Reeded. Some varieties have lettered edges reading "AUGUSTUS HUMBERT UNITED STATES ASSAYER OF GOLD, CALIFORNIA, 1851."

Varieties: Multiple die varieties exist, distinguished by lettered vs. reeded edges, target value expression, and die states. The K-series (Kagin numbering) categorizes these varieties.

Value by Condition

Damaged (mount removed, scratches, tooling): $25,000 - $50,000 Many surviving examples were mounted in jewelry, scratched during commercial use, or tooled (details re-engraved). The gold content alone is worth approximately $5,000-$6,000 at current prices, and the historical premium adds substantially.

VG-F (Very Good to Fine): $40,000 - $80,000 Heavy circulation wear. Major design elements visible but soft. The eagle and text are identifiable. These coins worked hard.

VF (Very Fine): $80,000 - $150,000 Moderate wear. Eagle feathers show detail. Text is fully legible. An attractive, problem-free example at this grade is highly desirable.

XF (Extremely Fine): $150,000 - $250,000 Light wear on high points. Most detail sharp. Some original luster in protected areas. Uncommon at this grade.

AU (About Uncirculated): $250,000 - $350,000+ Minimal wear. Strong luster. Exceptional for a large gold coin that was designed to circulate. Very few examples survive in this condition.

Known Variations

Lettered Edge (1851): "AUGUSTUS HUMBERT..." on the edge. The classic variety.

Reeded Edge (1851): Simple reeded edge without lettering. Different die pair.

880 THOUS. vs. 887 THOUS.: Gold fineness markings vary. Both are genuine Assay Office productions.

1852 dated slugs: Production continued into 1852. Same basic design with updated date.

$50 round (non-octagonal): Humbert's office also produced round $50 coins, which are a different series entirely.

Authentication and Fakes

Counterfeits are a significant risk given the values involved. Cast copies from genuine examples exist, as do struck forgeries.

Weight is critical: At ~83.5 grams of high-karat gold, these are heavy coins. Any significant deviation from the correct weight is a red flag.

Specific gravity testing: Gold has distinctive density. Non-destructive specific gravity testing can detect base-metal counterfeits.

Die diagnostics: Genuine examples show documented die characteristics. Professional authenticators at PCGS and NGC have extensive reference materials.

PCGS and NGC certification is essential. Both services regularly grade and authenticate territorial gold issues. For coins in this value range, professional authentication is non-negotiable.

Where to Sell

Heritage Auctions: The premier auction house for US coins, including territorial gold. Their auction catalogs for major sales attract serious collectors of Gold Rush-era material.

Stack's Bowers: Strong track record with early American and territorial gold.

Specialist dealers: Dealers like Kagin's (who literally wrote the reference book on California gold) are ideal for private treaty sales.

Expected costs for a $100,000 sale: PCGS/NGC grading: $250+. Insured shipping: $500+. Auction commission: 10-15%. Net to seller: $83,000-$90,000.

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