Following Wonder Africa, financed by three anniversary-celebrating companies, Gerard de Boe created a separate film for each, entirely devoted to their activities. Two of these—Le trait d'union and Diamant, pierre précieuse—were released exclusively in French, while the third, Cobalt au Katanga, also received a Flemish release. This scientific yet accessible documentary presents the industry and social achievements of the Union Minière du Haut-Katanga with clarity, sobriety, and objectivity, offering viewers an insightful glimpse into both enterprise and community impact.