PACS 61.46.Bc -Structure of clusters (e.g., metcars; not fragments of crystals; free or loosely aggregated or loosely attached to a substrate) PACS 68.43.Hn -Structure of assemblies of adsorbates (two-and three-dimensional clustering) Abstract -Noble metal nanoclusters (NCs) protected with thiolate ligands have been of interest because of their long-term stability that makes them suitable as building blocks for diverse assembled systems with emergent and improved functions. Despite the advances in synthesis and characterization, the mechanisms that contribute to their stability are still poorly understood. In this article, we review the different criteria that have been used to explain the experimental stability of NCs with a well-defined number of atoms that are protected with thiolate ligands. We discuss why these criteria are not enough to explain the stability. We conclude that there are other physical factors that should be included when explaining the stability of these systems and could be important for the discovery of new noble-metal NCs.