A brief description of a new class of strongly scattering dielectric microstructures. also called photonic material is given. These crystals are speculated to be of fundamental importance in the present day technology like semiconductors. The main theoretical and experimental developments are given. We have also calculated relative width of the Photonic band gap as a function of refractive index and a comparison is given for the close packed and diamond lattice of fee 3-D structure. The characteristics of liquid crystal as Photonic crystal are re-analyzed. This work may be fruitful for the investigators in the field of Photonic Crystals.