The present study attempts to focus on: why several informal localized industries are concentrated in specific geographical clusters and why not in others. In this sense, the study objects to detect the factors that determine location of informal industries in specific spaces, influences of these determinants to localized industry formation, and cost-effectiveness of setting up of production in such spatial clusters. To reveal these, the study is confined to two specific sites of West Bengal Gems and Jewellery industry, namely Bowbazar and Sinthi. The sites have been selected on the basis of their importance to the map of the industry by following a ‘core-ancillary’ formal-informal pattern of linkage. The logical argumentation of the study is based on literature support specifically of the classical and new economic geography school, case studies conducted, and the primary survey results. The micro-level field surveys, sampling design and data analysis are based on the standard model approach to avoid spatial homogeneity.