This paper presents cases of grammaticalisation leading to the formation of new suffixes in Persian and Azeri. Persian already features the suffix -gune (related to the suffix -gun, cf. gun “colour, type”), whose use in all Persian varieties (Iranian Persian, Dari, Tajik) is a sign of a relatively old grammaticalisation. More recently, the suffix ‑ṭ ōr (from ṭour “sort”) has emerged, albeit only in Iranian Persian. In Azeri, the suffix ‑təhər (from təhər “type,” likewise from ṭour) has been widely acknowledged, and its use predating that of -ṭōr in Persian suggests an independent grammaticalisation. Colloquial Azeri has also seen the emergence of the suffix ‑fason (from Russian fason, from French facon). The data indicate that all of the above suffixes are adjectival, carrying the meaning “being of the type, of the kind; having the quality of.” We offer a diachronic description of these suffixes and their synchronic analysis in Persian and Azeri.