Dedicated to Professor Manjanath Subraya Hegde on the occasion of his 65th birthday Molecular quantum clusters of noble metals are a fascinating area of contemporary interest in nanomaterials. While Au 11 , [1] Au 13 , [2] and Au 55 [3] have been known for a few decades, several new clusters were discovered recently. These include Au 8 , [4] Au 18 , [5] Au 25 , [6] Au 38 , [7] and so on. Au 11 has also been the subject of recent research. [8] In view of their luminescence, several of these clusters are expected to be important in biolabeling [9] and fluorescence resonance energy transfer [6f] as well as for creating luminescent patterns. [10] There are many examples of template-assisted synthesis of water-soluble luminescent silver clusters [11] with cores ranging from Ag 2 to Ag 8 , having characteristic electronic transitions between 400-600 nm. However, unlike the case of gold, there are only limited examples of monolayer-protected silver analogues. Silver clusters protected with aryl, [12] aliphatic, [13] and chiral [14] thiols have been reported, some of which have characteristic optical [12b, 13, 14c] and mass spectrometric [12a, 13, 14c] signatures. There is also a family of well-characterized metal-rich silver chalcogenide clusters. [15] Besides single-crystal diffraction, [15] mass spectrometry [15c,e] has also been used for detailed understanding of these clusters. Ag I clusters with [16] and without [17] luminescence have also been reported. Herein we present gram-scale syntheses of two luminescent silver clusters, protected by small molecules containing thiol groups, with well-defined molecular formulas, by interfacial synthesis. This new synthetic approach has become promising in several other areas including semiconductor nanoparticles, two-dimensional superlattices, and 3D structures. [18] A crude mixture of red-and blue-green-emitting clusters Ag 8 (H 2 MSA) 8 and Ag 7 (H 2 MSA) 7 (H 2 MSA: mercaptosuccinic acid), respectively, was synthesized in gram quantities by an interfacial etching reaction conducted at an aqueous/ organic interface starting from H 2 MSA-protected silver nanoparticles (Ag@H 2 MSA) [19] as precursor (for details see the Experimental Section and Figure S1 in the Supporting Information). During the reaction, the optical absorption spectrum of the aqueous phase showed gradual disappearance of the surface plasmon resonance at 400 nm (Figure 1 A) of metallic silver nanoparticles. The color of the aqueous