We prepared four different batches of silver nanoplates with different colors (maxrange from 600 to 500 nm) by adjusting the amount of NaBH4used in preparation, and studied the interaction between these four batches of silver nanoplates and iodide. The results showed that the four batches of silver nanoplates had thesimilar spectral change regularity in the presence of iodide (see Supporting Information, Fig. S7). As our colorimetric method proposed here is not based on comparing the gradual color changes in the presence of the analyte and standard, but finding the criticalcolor in a color change process. The discriminating of a critical coloris so easy, although the solution color and the critical color for each batch of silver TNPs are different.