This image was created for a training company to use on their Adobe Illustrator course pages. What I wanted to demonstrate with this is the level of detail you can achieve with a 2D vector package. For the foreground marble that appears static, I created the marble shape first, made the bottom side darker and added some reflections.
Once that was done, I created the inside of the marble and chose my colours carefully so that they worked together.
Then I added a shadow and tried to emphasise light passing through.
Finally, I created copies of it, changed the inside colours and made them different sizes for a sense of depth for the background marbles. Then I added some motion blur to give a sense of them spinning.