<title> SUMMARY </title>Refractometers have been standard laboratory tools since the eighteen ninties. With widespread use, the original Zeiss Abbe refractometer speciated to fill a variety of niches in research and industry. The expanding importance of the laboratory ensured the production of and development of Abbe refractometers by other firms after World War One. Competition and the changing work force pushed instrument evolution towards greater ease of use. Limitations of the Abbe design resulted in efforts to create more precise instruments to meet demands of research and industry, some instruments based on the Abbe, and others on different principles.