Ruby
Srimad-Bhagavatam
SB Canto 3
SB 3.15.44, Translation:
The Lord's beautiful face appeared to them like the inside of a blue lotus, and the Lord's smile appeared to be a blossoming jasmine flower. After seeing the face of the Lord, the sages were fully satisfied, and when they wanted to see Him further, they looked upon the nails of His lotus feet, which resembled rubies. Thus they viewed the Lord's transcendental body again and again, and so they finally achieved meditation on the Lord's personal feature.