Albert Barnes Commentary Lamentations 4:7

"Her nobles were purer than snow, they were whiter than milk; They were more ruddy in body than rubies, their polishing was as of sapphire." — Lamentations 4:7 (ASV)

The Nazarites from their temperance were remarkable for health and personal beauty, besides being held in religious veneration.

Rubies - Or, corals.

Their polishing was of sapphire - Or, their shape was “a sapphire.” The allusion is no longer to color, but to form. Their shape was exact and faultless as the cutting of a precious stone.