This thought-provoking essay strives to theorize the concept of ‘regimes of value’ and, more specifically, the role of material objects in the convertibility of different orders of value in the making of modern economies and societies. Put forth by Arjun Appadurai in his edited volume The social life of things (1986), the notion of regime of value originally referred to the use of categories of material objects in the construction of value within a specific cultural context. Appadurai was more concerned with the way value is invested in objects than in theories of exchange and currency, consequently the notion remained relatively untheorized. Jean and John Comaroff break new theoretical ground in at least two ways. First, they take into consideration and juxtapose different regimes of value – primarily cattle for the southern Tswana peoples and currency for the European colonizers – to see how they are constructed and become the focus of complex mediations between these groups in the colonial context of South Africa. Cattle, like currency (in the form of coins or paper money), come to objectify value because they have the power to make or break social relations, to build new social hierarchies or overturn old ones, to do or undo moral economies. They show that different regimes of value can coexist in the same social space and be played out against one another. Second, Jean and John Comaroff interrogate the role of conversion, or ‘commensuration’, as they say, of regimes of value, that is, their power to make objects from different cultural contexts universally objectifiable, comparable and negotiable. Instead of making difference, as is usually thought, it is the capacity to negate difference and make all things equal that expresses the effectiveness of a regime of value. It is also these processes of commensuration and conversion that give material objects their magical qualities, through which they become fetishized and ‘seem to have a power all of their own’ (p. 131). More than the written word or oral discourse, it is material objects that become the preferred tools and means of colonial domination. The authors contribute then to a better understanding of the workings of political economies as well as to the materialities of colonialism.