Corvettes, frigates, destroyers, today's fashion is brought to gigantism.
today there are destroyers that have a displacement that in the recent past identified a cruiser, and frigates with a displacement that was once that of light cruisers.
I think that to consider a ship as a corvette, frigate or destroyer is not the displacement, but the missions that these ships can achieve with the type of systems they have on board.
I want to remember that the destroyers in the period of the 1st world war had a displacement of less than 1000/1200 tons, in the second world war the displacement ranged from 1200 tons to less than 2500 tons.
Now we have USNavy 10,000 tons destroyers and Russian projects with 18,000 displacement!?! "Leader" class,
more or less the displacement of the
German heavy cruiser Prinz Eugen
therefore, even if I think it is an exaggeration to identify the Jamaran, Damavand and Sahand as destroyers, nothing forbids the Iranians, by type of mission assigned, to identify them as such.
I personally regard them as real frigates.