A micro-reflectance spectroscopy was performed on a single island of photonic crystal array. An array of islands of photonic crystal with colloidal polystyrene beads was assembled on Si using ink-jet printing. The polystyrene colloids with three different sizes (190 nm, 210 nm, and 270 nm in diameter) were used and the polystyrene colloidal particles were self-assembled to form fee lattices with three different lattice spacing. It was observed from the reflectance spectra that the position of the optical stop band shifts as the size of the colloidal particle changes. Effective medium approximations were used to model the dielectric properties of the colloid/air composite. The theoretically expected reflectance peak position agrees well with those of the experimentally observed peaks. The effect of finite size of the photonic crystal island on its reflectance spectroscopy was investigated by comparing the reflectance spectra collected from four different photonic crystal islands assembled from the same polystyrene colloidal particles, but with different lateral size for each island. It was found that the primary reflection peak was broadened and its intensity was reduced when the lateral size of the island was decreased.