The -diagnosis is a diagnostic strategy at system level that can significantly enhance the system's self-diagnosing capability. It can detect up to faulty processors (or nodes, units) which might include at most misdiagnosed processors, where is typically a small number. Somani and Peleg ([26], 1996) claimed that an -dimensional Star Graph (denoted ), a well-studied interconnection model for multiprocessor systems, is -diagnosable. Recently, Chen and Liu ([5], 2012) found counterexamples for the diagnosability obtained in [26], without further pursuing the cause of the flawed result. In this paper, we provide a new, complete proof that an -dimensional Star Graph is actually -diagnosable, where , and investigate the reason that caused the flawed result in [26]. Based on our newly obtained fault-tolerance properties, we will also outline an diagnostic algorithm ( is the number of nodes in ) to locate all (up to ) faulty processors, among which at most fault-free processors might be wrongly diagnosed as faulty.