The reciprocal element of a clasp assembly should be located at the gingival 1/3rd because it provides rigid stabilization without engaging undercuts that would interfere with the path of insertion or removal. Placing the reciprocal element gingivally ensures it balances the lateral forces exerted by the retentive clasp arm on the tooth and prevents unwanted tooth movement. This location also minimizes gingival irritation and maintains patient comfort. Proper positioning preserves tooth structure and enhances the overall stability of the removable partial denture.

Reference: Prosthodontics – Principles and Management Strategies, Deepak Nallaswamy, 2nd Edition.