GIA Reveals Why Diamonds Are Blue

Diamond Education

Blue diamonds may get their color from traces of boron contained in the floors of ancient oceans, according to research by the Gemological Institute of America (GIA).

The research lab studied mineral inclusions in 46 blue diamonds submitted to the GIA for grading over a two-year period.

The group, led by GIA research scientist Evan Smith, found that these stones originated at depths reaching 410 miles or more into the earth’s lower mantle. The diamonds formed in deeply sunken, ancient oceanic tectonic plates. The scientists believe the boron made its way to the earth’s interior through movement of those plates.

“Blue diamonds, like the famous Hope diamond, have intrigued scientists for decades, but the rarity and high value of these gems and their near lack of mineral inclusions have been major hurdles to research,” said Smith. “The opportunity to study these rare diamonds at GIA gave us insight into their incredible origin.”

GIA conducted the study together with researchers from the Washington-headquartered Carnegie Institution for Science, the University of Cape Town, South Africa, and the University of Padova in Italy. The results were published in the scientific journal Nature.