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Howard G. Coopersmith Diamond Geology and Mining Collection

Identifier: AHGC

Scope and Contents

The Howard G. Coopersmith Diamond Geology and Mining Collection consists of materials dated 1959 to 2017, with the bulk falling from 1987 to 2000. Material types include documents, maps, photographs, slides, videotapes, and electronic files. The collection contains correspondence, newspaper clippings, research notes, reports, publications, plans, and permits related to the Kelsey Lake mining project as well as to diamond projects around the world, and reference materials about diamond geology and mining in general.


  • Creation: 1959-2017
  • Creation: Majority of material found in 1987-2000


Restrictions on Access

There are no access restrictions on this collection. However, it is stored off-site, so advance notice is required.

Restrictions on Use

Not all of the material in the collection is in the public domain. Researchers are responsible for addressing copyright issues.


Geologist and diamond mining expert Howard G. Coopersmith served as a founder and president of Diamond Company N.L. (1987-2001) and as an officer/director of several public and private diamond exploration and mining companies before focusing on technical consulting to the industry. Diamond Company N.L. and its corporate associates operated the only modern diamond mine in the United States at Kelsey Lake, on the Colorado / Wyoming border. The Kelsey Lake mine was one of the first commercial diamond mines in North America, second only to mines at Prairie Creek (now Crater of Diamonds State Park), which operated in Arkansas during the early 1900s.

Born in Los Angeles, California in 1953, Coopersmith lived in California through his high school years. While working in a biochemistry lab at Colorado State University (CSU) in 1971, he applied to CSU's Geology undergraduate program. He went on to earn a bachelor's degree in Geology in 1975, and while pursuing graduate studies in that field was involved with the CSU research team that discovered the first diamonds in northern Colorado in 1976. His graduate studies were supported by Canadian mining company Cominco, for which he worked full time managing diamond exploration from 1977 through 1986. During this period many important discoveries were made in the Colorado/Wyoming State Line Diamond District.

Coopersmith married Cynthia M. ("Cindy") Valko in 1983 at a ranch near Virginia Dale, Colorado. The potential of the Kelsey Lake (KL) diamond site was identified shortly after their daughter Sheila was born in 1987, culminating in a mining lease with the private ranch encompassing the site. With Coopersmith heading the project, the Australian-based Diamond Company N.L. conducted preliminary sampling and prospecting, applying for permits in 1992 to conduct the second phase of exploration at the Kelsey Lake site.

After collecting thousands of small diamonds in the area, in late 1993 the company unearthed a 6.2 carat gem-quality specimen at the site. In June of 1994 an almost flawless 14.2 carat gem diamond was discovered there, the sixth-largest diamond ever found in North America. Shortly after the 1996 discovery of a yellow 28.3 carat gem named the "Colorado Diamond" (the largest diamond unearthed at the site), Diamond Company N.L. and then parent company Redaurum Ltd. were sued by the Union Pacific Land Resources Corporation, which claimed that Union Pacific had retained mineral rights after selling the land in 1896. A settlement was reached in 1997, and trial mining continued. However, the expense of the lawsuit at a time when junior miners worldwide were experiencing financing difficulties resulted in gross undercapitalization of the project. This resulted in deferral of purchasing important processing equipment, such as a primary crusher and x-ray diamond sorting machine, and inefficient ore processing and diamond recovery. Redaurum abandoned the project, and legal and financial troubles continued.

McKenzie Bay International Ltd. purchased the mining operation in 2000 and invested in new mining equipment, and Coopersmith accepted a position as vice president for diamond production. Within a year, the rising market value of vanadium led McKenzie Bay to turn its attention to developing a large vanadium deposit in Canada, and the diamond mine was offered for sale. Prospective buyers (Roberts Construction Company of Wyoming and BJ+J diamond sellers of Boulder) were deterred by a dispute with the landowner regarding project commitments and royalty payments, and McKenzie was unable to find another buyer. All mining operations ceased by the end of 2001, and the site was fully reclaimed by 2006.

Coopersmith's unique experience and expertise in the field, particularly his knowledge of diamond mining, led him to many consulting assignments throughout the world. His pioneering work related to American diamonds is ongoing.


42.75 linear feet (28 record cartons, 2 document boxes, 25 map folders)

Language of Materials



Howard G. Coopersmith, a geologist and diamond mining expert, was a founder and president of Diamond Company N.L., and an officer/director of several public and private diamond exploration and mining companies before focusing on technical consulting to the industry. The collection consists of reference documents about diamond mining in general as well as materials related specifically to the Kelsey Lake diamond mining project and other diamond projects around the world. Materials include research notes, reports, plans, permits, publications, clippings, maps, photographs, and electronic files.


This collection is divided into series based on the donor's arrangement order.

The collection consists of 10 series in 30 boxes and 3 USB drives:

Series 1: Series 1: Kelsey Lake (KL) geology and exploration, 1978-2005

Series 2: Kelsey Lake corporate records, 1984-2003

Series 3: Kelsey Lake equipment, 1992-2002

Series 4: Kelsey Lake land and permits, 1959-2006

Series 5: Kelsey Lake operations and sales, 1981-2003

Series 6: Non-KL Colorado/Wyoming kimberlite, 1978-2013

Series 7: Non-KL corporate, 2006-2010

Series 8: HGC [Howard G. Coopersmith] papers, 1975-2011

Subseries 8.1: Consulting work, 1985-2011

Subseries 8.2: Conference/meeting materials, 1977-2011

Subseries 8.3: Other HGC materials, 1975-2007

Series 9: Kimberlite reference materials, 1963-2014 and undated

Subseries 9.1: Kimberlite USA, 1963-2001

Subseries 9.2: Kimberlite/diamond geology, undated

Subseries 9.3: Kimberlite-Canada, 1986-2014

Subseries 9.4: Kimberlite/lamproite-Australia, 2007

Subseries 9.5: Kimberlite/diamond-South America, 1998

Subseries 9.6: Kimberlite/diamond-other areas, undated

Subseries 9.7: Kimberlite/diamond-Africa, 2004

Subseries 9.8: Kimberlite/diamond General Geology, 1974-1994

Subseries 9.9: General diamond reference material, undated

Series 10: Electronic files, 1998, 2006-2017


Howard G. Coopersmith donated most of the collection to the Colorado State University Libraries on June 24, 2016. He donated additional materials on May 4, 2017.

Related Collections

The Colorado State University Archives also holds the Records of the Department of Earth Resources (1966-2000).


Initial processing was completed in May, 2017. Minimal processing standards were applied in order to expedite access to the collection. Materials were rehoused in acid-free boxes, and re-foldering in acid-free folders was implemented as necessary. Additional processing was undertaken and completed in July, 2019.

Inventory Note

Note: Title information supplied by the archivist is bracketed.

Guide to the Howard G. Coopersmith Diamond Geology and Mining Collection
Edited Full Draft
Prepared by Natalie Pace, Jessica Gengler, and Dax Collazo
Copyright 2020
Language of description
Script of description
Language of description note
Finding aid written in English.

Repository Details

Part of the CSU Libraries Archives & Special Collections Repository

Fort Collins Colorado 80523-1019 USA