A rapid and readily reproducible seed-based method for the production of high quality silver nanoprisms in high yield is presented. The edge-length and the position of the main plasmon resonance of the nanoprisms can be readily controlled through adjustment of reaction conditions. From UV-vis spectra of solutions of the nanoprisms, the inhomogeneously broadened line width of the in-plane dipole plasmon resonance is measured and trends in the extent of plasmon damping as a function of plasmon resonance energy and nanoprism size have been elucidated. In addition, an in-depth analysis of the lamellar defect structure of silver nanoprisms is provided that confirms that the defects can lead to a transformation of the crystal structure in the vicinity of the defects. These defects can combine give rise to lamellar regions, thicker than 1 rim, that extend across the crystal, where the silver atoms are arranged in a continuous hexagon al-close-packed (hcp) structure. This hcp structure has a periodicity of 2.50A, thus explaining the 2.50A lattice fringes that are commonly observed in 111) oriented flat-lying nanoprisms. A new understanding of the mechanisms behind anisotropic growth in silver nanoprisms is presented.