Stephen Kotkin, Stalin, Vol. II: Waiting for Hitler, 1929–1941Hitler had sent his personal photographer so that the Führer could study Stalin’s surroundings as well as his physiognomy, for Hitler was anxious to ascertain whether Stalin’s earlobes were “ingrown and Jewish, or separate and Aryan”?
Alan Bullock, Hitler and Stalin: Parallel LivesHe believed these would show whether Stalin had Jewish blood - whether the earlobes were 'ingrown and Jewish, or separate and Aryan’. He was relieved to see that Stalin passed the test and was not a Jew.
AFAIK, Georgians were considered to be Aryans. But, I’m sure that Hitler would have been aware of the rumours that Stalin had Ossetian ancestry which would also have been considered Aryans (Indo-European).
On a side note, did the Nazis use this method on German citizens who they thought were Jews?