Gold nanoshells are new constructional units consisting of dielectric core encapsulated by gold nanolayer that exhibits a plasmon-derived optical resonance typically shifted to near-infrared (NIR) wavelengths (800∼1200 nm). The fabrication of gold nanoshell was optimized based on the relative contributions of the aging of gold colloids, concentration of reducible gold salts, and dosages of formaldehyde reducing agents. One-week-aged gold colloids produced a relatively monodisperse deposition of gold seeds onto silica nanoparticles, whereas one-day-aged gold colloids produced a heterogeneous deposition of gold seeds on the silica nanoparticle surfaces. At the optimal dosages of reducing agents, the thickness of the gold layer increased with the increment of the concentrations of the reducible gold salts, consequently leading to the smoother morphologies and stronger plasmon resonances of the gold nanoshells. The excessive addition of gold salts and/or reducing agents, however, resulted in a significant reduction of the plasmon resonance because of the increased aggregation between the gold nanoparticles.