The Biggest Diamond Found in Arkansas: Carat-Size Glory

The question of what is the biggest diamond found in Arkansas centers on the legendary Uncle Sam Diamond, discovered near Murfreesboro. This rough stone remains the most famous crystal unearthed from the state's public search fields and continues to attract rock enthusiasts from around the world.

Below is a concise reference that captures key data about Arkansas diamonds, including size, color, notable records, and visitor details for planning a trip to search for diamonds.

The History of Diamond Mining in Arkansas

The Crater of Diamonds State Park preserves the only diamond-producing site in the United States open to the public. This field formed over 95 million years ago during intense volcanic activity, bringing diamonds to the surface in a weathered geologic pipe. Local records from the early twentieth century describe commercial operations that attempted to mine the deposit before it became a protected state park.

The Uncle Sam Diamond Details

Physical Characteristics

The Uncle Sam Diamond weighs 40.23 carats and was found as a rough crystal with a distinctive double-terminated shape. Its near-colorless appearance and large size make it stand out even among other Arkansas finds. The stone was not faceted, preserving its natural form for display and study.

Discovery Context

Wesley Oley Basham discovered the stone in 1924 while manually sifting surface material at the site. At the time, miners focused on visible metallic minerals, but the unusual clear crystal drew attention from geologists and collectors. Early documentation noted the difficulty of extracting such a fragile structure from the matrix without damage.

Record-Breaking and Visitor Diamonds

While the Uncle Sam Diamond holds the record for the largest rough stone found in Arkansas, other notable crystals have reinforced the state's reputation. The public search fields allow visitors to keep any diamond they discover, encouraging thousands to test sieves and patience each year. Prospecting rules emphasize surface collecting only, preserving deeper geological context for researchers.

Visiting the Crater of Diamonds

Search and Access Information

Crater of Diamonds State Park charges a modest fee for entry, granting visitors several hours to hunt across designated acres. Tools such as screens, scoops, and sifters are available for rent, and staff provide guidance on where to focus efforts after rain events. Many guests report that persistence in eroded stream channels increases the likelihood of spotting small stones.

Identification and Certification

On-site staff assist with preliminary identification, sending promising specimens to professional labs for certification. Certification confirms weight, measurements, and whether the stone has undergone commercial treatment. Visitors who find diamonds receive documentation that supports insurance, appraisal, and potential sale decisions.

Key Takeaways for Diamond Prospectors

• The biggest diamond found in Arkansas is the 40.23-carat Uncle Sam Diamond.
• Crater of Diamonds State Park is the only active public diamond field in the United States.
• Most surface diamonds discovered are small, but rare large crystals still appear.
• Documentation and professional certification help establish value and authenticity.
• Following park rules and searching after rain improves the chances of a meaningful find.