Design, control, and direct characterization of surface properties are prerequisites to all the practical applications of nanoparticles. Since stable and homogeneous colloidal conditions are required for most applications, the amenability of nanoparticles to in-solution processing must also be addressed. Herein, we demonstrate that solution H-1 NMR spectroscopy is an effective tool for direct monitoring of the production of Ag nanoparticles. The production consists of two stages, complexation and reduction, which are both clearly observed by H-1 NMR spectroscopy. Design and synthesis of a series of amphiphilic amines have led to the one-step production of "flexibly" stable colloidal Ag nanoparticles, which form clear stable brown solutions in a wide range of solvents.