Srimad-Bhagavatam: Canto 8 - Chapter 1 - Verse 17

Sanskrit:

यत्र नित्यवयोरूपा: श्यामा विरजवासस: ।भ्राजन्ते रूपवन्नार्यो ह्यर्चिर्भिरिव वह्नय: ॥ १७ ॥

ITRANS:

yatra nitya-vayo-rūpāḥśyāmā viraja-vāsasaḥbhrājante rūpavan-nāryohy arcirbhir iva vahnayaḥ

Translation:

Everlastingly beautiful and youthful women, who were dressed with clean garments, glittered in the city like fires with flames. They all possessed the quality of śyāmā.

Purport:

Śrīla Viśvanātha Cakravartī Ṭhākura gives a hint of the quality of the śyāmā woman. A woman whose body is very warm during the winter and cool during the summer and who generally has very firm breasts is called śyāmā.