Is Moomin mug Dive with seashells the most expensive Arabia Moomin mug or does it even count as one? 

There are rumours saying that only 10 of these were made before abandoning the design and choosing to make the mug without seashells instead. The mug looks otherwise the same, only difference being the missing seashells.

At least some of the test versions were given to Arabia’s employees at the factory.