This data is featured in the supporting information section of “Functional carbon nitride materials — design strategies for electrochemical devices” by Bojdys et al. in Nature Reviews Materials 2017, Article number: 17030 (2017), DOI: 10.1038/natrevmats.2017.30 So-called “graphitic carbon nitride” or “g-C3N4” is actually a linear polymer. Here, we analyse a commercially available product that doesn’t quite hold up to scrutiny. The here-presented physical data was compiled in March 2013 (internal report with permission from the University of Liverpool, Department of Chemistry, UK). It should serve as a sanity-check to facilitate quick identification of (C6N8) melon-type samples and aid in phase identification even in tricky cases: e.g. melon is chemically and physically indistinguishable from Nicanite® that was marketed as a “high purity, graphitic carbon nitride” by Carbodeon.