The most detailed account I've seen is from Montefiore (2003):
On the 8th, after another meeting, they dined with Stalin at the
Yusupov Palace [...] This epic dinner boasted one unusual guest: Stalin invited a delighted Beria, who was beginning to find his secret role
constricting. Roosevelt noticed him and asked Stalin: 'Who's that in the pince-nez opposite Ambassador Gromyko?' 'Ah, that one. That's our Himmler,' replied Stalin with deliberate malice. 'That's Beria.' The secret policeman 'said nothing, just smiled, showing his yellow teeth' but 'it must have cut him to the quick', wrote his son, who knew how he longed to step on to the
world stage. Roosevelt was upset by this, observed Gromyko, especially since Beria heard it too.
Unfortunately Montefiore is rather vague about his sources. He quotes a description of the dinner from Alan Brooke's diary, which describes Stalin as "full of fun and good humour apparently thoroughly enjoying himself," but Brooke makes no direct mention of the relevant exchange. Sergo Beria's book does indeed state that Stalin "presented my father to Roosevelt as ‘our Himmler’," but provides almost no further detail about the actual episode at Yalta (or any other context in which Stalin may or may not have used the same line).
Critically though, in a footnote, Sergo Beria does indicate Gromyko as the eyewitness source of the story from Yalta and attributes the description of his father's "yellow teeth" to him. Here Beria (and also Parrish (1993)) cites a 1991 book by V. F. Nekrasov called Beria: Konets karery. Hopefully someone who reads Russian can dig that one up and follow the trail.