Some help for the interpretation of the Cole-Cole plot can be got from the following paper

D. R. Saini, A. V. Shenoy and V. M. Nadkarni, Dynamic mechanical properties of highly loaded ferrite-filled thermoplastic elastomers, J. Appl. Polym. Sci., Vol. 29, p. 4123-4143 (1984).

In this paper, the  storage (real)  and  the  loss (imaginary) components of the complex modulus were written explicitly in the form of the Wiechert  model.  The general practice is to use one Wiechert arm for each observed transition and assign a single relaxation time to each transition.  Single  relaxation time  model, theoretically, would  not  provide  a complete  description of the  experimental data, since  the  molecular mechanisms involved  even  in  a single  transition are sufficiently dissimilar to create a wide distribution of relaxation times. One means of improving the model is to assign several Wiechert arms to each transition. Another approach is to modify the equations slightly to include a Cole-Cole broadening parameter on each arm. A convenient means of selecting the parameters for the Wiechert model is to employ the Argand  diagram in which E" is plotted as the ordinate against E' as the  abscissa.  In the case of single-relaxation time transitions, this diagram appears as a semicircle which intersects the abscissa  at  the  maximum and  minimum storage moduli. In the  case of the distributed relaxation times,  the semicircles are  depressed  to arcs,  and  it can be shown  that the  height  of the arc is directly related to the Cole-Cole broadening parameter.

Thank you so much sir for your answer. But my confusion is about the part which forms the spiral. The Semi circle can be attributed to grain contribution but my figure goes beyond the semi-circular loop and gives the feel of being a spiral. So how do I interpret that?

Hi Sandip,

Generally this type of behavior is observed if you have any inductive component. Then you have two time constants associated to the plot in the low frequency regime. I am not sure about the system your are dealing with, but you can go through this link for basic information about this type of Nyquist plot.

http://www.consultrsr.net/resources/eis/induct2.htm