While other diamonds get their color from chemical impurities that absorb light (yellow from nitrogen, blue from boron) the “pink” in pink diamonds remains a mystery – since no similar impurities have been found in pink diamonds. In a BBC.com piece dedicated to the “rise and rise” of pink diamonds in recent years, the BBC spoke to experts who are trying to unravel the mystery around the rarest of all diamonds.
The newly ignited interest in the formation of the color in pink diamonds stems from a reserve of brown and pink diamonds found in the Argyle mine in Australia. Argyle, owned by mining giant Rio Tinto, is the world's largest source of pink diamonds. According to the BBC, scientists have already examined the cache using various instruments (a mass spectrometer among them) to examine the diamonds for any trace of impurities. So far, no impurity can be associated with the pink color in diamonds.
A focused ion beam used to cut the surface of the diamonds has found that most pink diamonds are not uniformly pink but have “pink zones that alternate with clear areas”. These, the experts speculate, were formed by some shock, possible seismic, that altered the stone’s molecular structure and thereby, its color. So far, the fascinating investigation into the pink color of the diamonds is still under way.