Something very exciting landed on my bench — and it's absolutely having a moment in the US. In the early 2000s, miners in Vietnam started finding small pink sapphires with a truly unusual effect: slightly hazy, milky stones that blazed with dozens of inner sparks. They are sometimes called opalescent sapphires.
The effect isn't magic — it's physics. Inside the corundum crystal there are tiny titanium dioxide nanoparticles (TiO₂), roughly 10–40 nm in size, known as rutile silk. Their size is close to the wavelength of visible light, so they scatter it in a very particular way, creating that milky glow with vivid flashes from within. Critically, every stone like this is unheated: when sapphires are exposed to high temperatures, the rutile inclusions dissolve into the crystal lattice and the effect is gone forever. Since the vast majority of commercial sapphires are heat-treated, genuinely "alive" milky stones are rare by definition.
They come primarily from the Luc Yen district in northern Vietnam, Yen Bai Province. The deposit sits within Upper Proterozoic to Lower Cambrian marbles along the eastern margin of the Red River shear zone — a geological setting that gives these corundums their characteristic pink-to-purple colour and the high titanium content that makes the whole effect possible.
Not long ago, these were niche curiosities picked up by oddity hunters for a few hundred dollars. Over the past couple of years, they have become a serious collector obsession — arguably hotter than fine cobalt spinel. Prices have risen by multiples in a very short time.
This particular pair — over 3 carats each — has an extra twist: GRS certified them as rubies. We wouldn't have called it that ourselves, but who are we to argue with Dr. Peretti. Whatever sparks the iPhone managed to catch, multiply by five. I'll leave price predictions to someone braver.