Abstract
Berlin & Kay's basic colour term framework claims that there is an ordering in the diachronic development of languages' colour systems. One generalisation is that primary colours, WHITE, BLACK, RED, YELLOW, GREEN, BLUE, are lexicalised before derived colours, which are perceptual blends, e.g. ORANGE is the blend of YELLOW and RED. The colour systems of Lower Sorbian and Upper Sorbian offer an important typological contribution. It is already known that primary colour space can contract upon the emergence of a basic derived term; our findings indicate that derived categories also shift as colour systems develop. Tsakhur offers corroborating evidence.