<p>This work presents a self-explanatory R script to perform Stiff diagrams that are integrated into QGIS environment. Stiff polygons are widely used diagrams in hydrochemical studies that represent a particular chemical type for a water sample. To accomplish this task, the script creates a scalable vector file (svg) for each sample that are later integrated into QGIS by means of a QGIS Layer Style file (qml, after Qt Meta-object Language), which is essentially an XML-based file. This .qml style file allows positioning each polygon on a map using the rule-based symbology options. The R script also creates a complete (i.e., with references) Stiff diagram that is used in the legend of the final map in order to indicate which are the concentration that are being representing by each diagram. This tool was designed using exclusively open-source software programs. In addition, to avoid any dependence of R and QGIS version, as well as third-party plugins, no additional packages are required to be installed. Inexperienced and non-familiar R users will find that the script is easily executed since every step is clearly explained.</p>