It is a well-known fact that diamonds are among the rarest gemstones on Earth, naturally colored diamonds are even more so. So much so, that gemologists and geologists are still learning about how diamonds obtain color. The Gemological Institute of America (GIA) just published a report on blue diamonds. The study, conducted by GIA, took place over two-years using 46 blue diamonds submitted to the GIA.

Colored Diamonds – Blue Diamonds, A GIA Study

Evan Smith, a Lead Researcher at GIA, estimates that 0.02% of mined diamonds containing the trace element boron. Scientists largely conclude boron is responsible for natural blue diamonds color. This explains why in recent auctions, blue diamonds are fetching record prices. Moreover, finding these diamonds with natural, solid inclusions is even harder.

The Process

Gemologists concluded in this article that blue diamonds form an estimated 4 times deeper in the Earth’s mantle (most form between 93 – 124 miles below in continental plates brought up by Kimberlite eruptions). Researchers hypothesize diamonds fuse with boron in the sublithospheric mantle (superdeep) from oceanic rock. Furthermore, they state oceanic rocks are subducted 410 miles or deeper over a billion years by plate techtonics!

In addition, geologists make inferences from inclusions in these diamonds. This information tells gemologist about the surrounding minerals and known locations of said minerals.