The Konica Pearl III uses 30.5mm filters. These are common due to the usage on contax and rollei compacts.
However, a regular depth filter may not allow the camera to close. You can still use it, just remember to remove before closing.
The original is super slim.
Walz did make filters for this camera, but it is hard to identify them because they were not labeled '30.5'. The clear UV filter is labeled '39.3' in various sizes.
The 'for konica 2.8 and pearl' kit from walz does NOT fit. That is for the original pearl.