Śrī Caitanya Caritamrta · Text Madhya 4.193
রত্নগণ-মধ্যে যৈছে কৌস্তুভমণি ।
রসকাব্য-মধ্যে তৈছে এই শ্লোক গণি ॥ ১৯৩ ॥
ratna-gaṇa-madhye yaiche kaustubha-maṇi
rasa-kāvya-madhye taiche ei śloka gaṇi
As the Kaustubha-maṇi is considered the most precious of valuable stones, this verse is similarly considered the best of poems dealing with the mellows of devotional service.
Read this verse on Vedabase.ioThis verse has no purport; its meaning is explained by the verses around it.