This report describes the results and the learnings of a project that had the aim to develop a protocol for measuring circularity for products. The project was centered around an assessment of the real-world example of a lubrication cleaning and recirculation system by SKF RecondOil. The process of assessment required that the team match circularity in principle (how circularity can be measured in theory) with circularity in practice (how circularity can be measured in a real system). In the process, the team identified different ways to measure circularity based on drafted circularity principles (from ongoing ISO work on circularity). In the end, these alternatives were to be practically verifiable and certifiable. Learnings are to be fed into ongoing work on developing international standards (ISO) for assessing circularity. In the progress of the work, a framework for understanding and measuring circularity for the system at hand was developed including: a heuristic (diagram) describing a system of interest and a list of chosen circular economy principles see Figure 3. It is thought that the heuristic and list of principles could be used to guide an entity in the process of first, creating their system model, and then, making sense of and applying principles.