India, Oct. 3 -- "Heera ka haar (string of diamonds)," we say to a child, as an endearment.

It is a phrase that echoes in Hindi, Gujarati, Bengali, Malayalam, Tamil, Telugu, Punjabi.

That's just one example of how these inimitable gems, timeless and rare, echo through India's ancient culture, as a jewel to be worn and flaunted, but also as a metaphor: for something precious, enduring and powerful; something to be treasured, and held close.

The echoes go all the way back to the beginning.

In Sanskrit, the word "vajra" means both "thunderbolt" and "diamond", inextricably linking the gemstone with the God of storms, Indra. The vajra is his weapon, a symbol of invincibility.

Ancient texts link these gems, in different hues, to various de...