  Jammed matter is by definition impenetrable to light, rendering the
characterization of the 3D geometry difficult. Confocal microscopy of a dyed,
refractive index matched emulsion nevertheless allows one to image the jammed
system. Here we explain the origin of the mechanism of enhanced fluorescence at
the contacts of jammed emulsion droplets in terms of a blue-shifted
fluorescence emission band due to the change in the polarity of the interfacial
environment. We then use this information to determine the contact network in
the emulsion, which models a frictionless jammed system. This enables the
experimental determination of the average coordination number, $<Z >$ giving
the theoretically predicted value of $<Z > \approx 6$. Furthermore, the method
enables the experimental measurement of the entropy of the packing from the
network of contacts.
