| Singular | Plural | |
|---|---|---|
| Nominativ | diadema, diadema | diademata, diademae |
| Genitiv | diadematis, diademai, diademae | diadematium, diadematum, diademarum, diademum |
| Dativ | diademai, diademate, diademati, diademae | diademis, diademabus, diadematibus |
| Akkusativ | diademam, diadema | diademas, diademata |
| Ablativ | diadema, diademad, diademate | diademis, diademabus, diadematibus |
| Vokativ | diadema, diadema | diademata, diademae |