  We report ground-based spectrophotometry of KIC 8462852, during its first
dimming events since the end of the Kepler mission. The dimmings show a clear
colour-signature, and are deeper in visual blue wavelengths than in red ones.
The flux loss' wavelength dependency can be described with an \AA ngstr\"om
absorption coefficient of $2.19\pm0.45$, which is compatible with absorption by
optically thin dust with particle sizes on the order of 0.0015 to 0.15 $\mu$m.
These particles would be smaller than is required to be resistant against
blow-out by radiation pressure when close to the star. During occultation
events, these particles must be replenished on time-scales of days. If dust is
indeed the source of KIC 8462852's dimming events, deeper dimming events should
show more neutral colours, as is expected from optically thick absorbers.
