The Harris Diamond collection

The Harris Diamond collection has been donated to the University of Bern, by Dr. Jeffrey W. Harris and his wife Francesca Harris. Details can also be read in the media release of the University of Bern. Dr. Jeffrey Harris (Fig. 1a) is a diamond expert and over the years built up a collection of diamonds for research and teaching purposes through donations by The Diamond Trading Company Limited (DTC).

Jeffrey W. Harris and Suzette Timmerman
Figure 1: A) Dr. Jeffrey W. Harris, diamond expert and donor of the collection, is holding a Type II diamond. Photograph provided by Jeff Harris. B) Prof. Dr. Suzette Timmerman, chair of the diamond committee curating the collection. © University of Bern, Image: Dres Hubacher.

The Harris diamond collection is one of the largest research diamond collections in the world, with over 29.000 whole rough diamonds. Besides the almost 6000 carats of whole diamonds from known sources, it also contains >1000 carats of diamond fragments as remnants of previous scientific studies. The fragmented diamonds are not mixed thus can be still related to individual sources. The absolute value of the stones is limited, with an average of 10 USD per diamond. The scientific significance is, however, invaluable, with various locations no longer accessible, as mines have closed. The collection contains a range of diamond samples from micro-diamonds to macro-diamonds with lithospheric or sublithospheric mineral inclusions (Fig. 2) and from coated and fibrous diamonds to hailstone boart. It also has diamonds without inclusions, chosen for the variety of morphological and surface features.

Microdiamonds and diamond with a ferropericlase inclusion
Figure 2: A) Microdiamonds from Premier. B) A diamond with a ferropericlase inclusion from Sao Luiz. The diamond is approximately 7 mm in diameter. © University of Bern, Images: Dres Hubacher

The principal sources are highlighted on the map (Fig. 3). The vast majority is from Southern Africa; these include Jwaneng, Orapa, Damtshaa, Letlhakane, (Botswana), Premier, Finsch, DeBeers Mine, Wesselton, Dutoitspan, Bultfontein, Koffiefontein, Venetia, and Roberts Victor (South Africa).

Equal area projection
Figure 3: Equal area projection, with mining locations where the collection contains >50 stones. One symbol may represent multiple nearby mines on the map, due to its resolution. Map made with the assistance of Claude.

The aim of this well-documented collection is that through its curation in Bern it can remain available for the scientific community. Members of that community have already considerably benefited from diamonds that have come from this collection. We look forward to future discoveries of new minerals, new insights into subduction processes, formation of mantle roots below continents, mantle evolution, and other new knowledge about the history of our planet Earth.

Samples can be requested from this collection for scientific research. Please fill out the 'sample request form' and e-mail it to Prof. Dr. Suzette Timmerman: suzette.timmerman@unibe.ch. Only senior researchers (supervisors) can act as the PI for sample requests. The diamond committee - consisting of four people and chaired by Prof. Timmerman (Fig. 1b) - reviews the sample requests on a need-be basis.