The efficient and reliable operation of machinery and mechanical systems is of highest importance in our technological world. This holds also true for ball bearings, which are the focus of this work. The selection of the right materials for ball bearings is crucial to ensure longevity, wear resistance and optimal performance. In this context, structural ceramic materials such as silicon nitride have established themselves as a promising option due to their outstanding properties, including high hardness, corrosion resistance, thermal shock resistance and low weight. Despite these promising properties, structural ceramic materials are susceptible to failure due to cracking under load. Contact damage, especially Hertzian ring cracks, is a common damage mechanism in ceramic ball bearings. This master thesis aims to capture the forces involved in the formation of ring cracks (initial damage) in ball bearing balls and interpret them using the Hertzian contact theory. Instead of the typical contact between a ball and a flat plate, this study examines the contact between two balls under load (¿ball-on-ball compression test¿). A specially designed measurement setup acoustically detects the occurrence of ring cracks in the balls, reliably determining when contact damage begins in a ball-to-ball contact, making the first step toward the total failure of the ball bearing ball. To investigate the influence of ball diameter on initial damage and, consequently, on the Hertzian contact theory, balls with different diameters are tested. Additionally, some balls are heat-treated at different temperatures (¿annealing¿) before the test to explore changes in potential residual stresses on initial damage. The results of this work are intended to contribute to the improvement of silicon nitride ball bearings by providing insights into contact damage and its triggers, potentially leading to the development of more robust and durable components for demanding applications.