This paper presents some aspects of the contribution to the history of colors and dyeing technology to be expected from the comprehensive study of a rare type of historical document, which was not published and exploited until recently. It describes and compares several early– to mid–eighteenth century manuscripts of dye books or treatises on dyeing from England and France, having in common an essential feature: all are illustrated with scores of samples of dyed wool fabric. The French sources are the Memoirs on Dyeing of two dyework owners in wool broadcloth–producing centers in Languedoc in southern France. The English sources belong to the Crutchley Archive and consist of the dye books of a family-run dyed wool fabric business in Southwark, London. In this paper, the authors present the respective color gamuts of the French dyers and their contemporary colleagues in London. The paper begins with the study of corresponding dye recipes and the chromatic specifications of the samples based on color names, which were obtained through colorimetric measurements and expressed in the CIE Lab and CIE LCh systems of color description. Madder red is then proposed as a case study for comparisons of the dyeing processes and resulting chromatic effects in the English and French sources.