Although most stones found are small, some spectacular specimens have been found.

The “Uncle Sam Diamond,” the largest diamond ever found in North America, was found there in 1924. This pale brown, 40.23 carat stone was found in 1924 by W. O. Bassum. It was cut into an emerald-cut gem weighing 12.42 carats which was sold in 1971 for $150,000.

The “Strawn-Wagner Diamond” was found in 1990 by Shirley Strawn. This 3.09 carat stone was cut into a 1.09 carat brilliant-cut gem. It was the first stone to receive a perfect grade of 0/0/0 by the American Gem Society. A photo of the diamond can be seen on this page.

A number of beautiful colored diamonds have been found at the Park. The most famous is the “Okie Dokie Diamond” found in 2006 by Marvin Culver. This 4.21-carat canary-colored diamond was featured in a number of television programs and magazine articles. Yellow and brown diamonds of gem quality are regularly found at the mine.

Lamproite pipe: Simplified cross-section of a lamproite pipe and residual soil deposit. The “Crater of Diamonds” is part of a volcanic feature that is known as a “maar.”