Although most of the bluestones are just chips, there have been a few small objects (found at Stonehenge) made from bluestone which have been deliberately formed into disc shapes.
Given the similarity of bluestone to the night sky and when one looks at the Nebra disc, (which has a number of small gold discs on it which are presumed to represent stars) one could perhaps imagine the bluestone discs as playing the role of stars as well.

I grant you this is a tenuous connection, but I though I would throw it in!

Its perhaps a very small hint that Stonehenge played a similar role as has been suggested for the Lascaux caves in France....

Chris W