The low friction coefficient of HMPE fibers may be a disadvantage for some applications such as winches but it can also be used to develop new technology. Recently this specific property was used in the design of innovative pulleys for sailboats. The contact is then between a low friction metallic ring and a HMPE fiber rope loop. During service, a specific phenomenon appears at the contact area on the HMPE fibers called lustering due to its visual aspect. It is also observed in eye splice contact zones during tensile testing. In the present work, an investigation was made to understand and explain the appearance of the lustering of the fibers. Based on examination of different hypotheses, mechanical tests and a range of microstructural observations, the conclusion is that the appearance of the lustering phenomenon is the result of compaction of the filaments of the HMPE rope loop.