The following images and descriptions are example entries into the photo contest:
Image by: Martin Tauc
The sugar is between two crossed polarizes. You can see the effect most as you look away from the center (light source). The sugar crystals are significantly brighter than the surrounding area. Somehow, the structure of the sugar is modifying the polarization of the white light. Either the sugar contains some chirality in which case the linear polarization state is rotated, or it is birefringent and the orthogonal phase fronts get shifted and thus modify the polarization state. Either way, we see that a common substance such as sugar has the ability to modify polarization in an interesting way.
Image by: Dave Riesland
These photos show birefrengence; using reflection from a desk as the first polarizer, the reflection from the second surface of the ruler, and crossed polarizers.