expression, noun
rarity among rarities; rara avis; black swan
Emphatic set phrase meaning something extremely rare, literally 'rarity among rarities'. Used in both literal and figurative contexts.
この切手は珍中の珍で、市場にほとんど出回らない。
This stamp is a rarity among rarities and hardly ever appears on the market.
彼のような正直な政治家は珍中の珍だ。
An honest politician like him is a black swan.