The largest 468.30 carats gem-quality diamond in Russia history

ALROSA, PJSC recovered the largest gem-quality diamond in the country's history. The fancy amber-colored crystal weighing 468.30 carats and measuring 56x54x22 millimeters was extracted in Yakutia at Processing Plant No. 12.
The key role in diamond recovery is linked to operation of X-ray luminescence sorters LS-20-05-2N and LS-OD-50-03N manufactured by Bourevestnik, JSC., which once again confirmed their high efficiency in real production.
The company's specialists say with confidence that this discovery is not just a fluke, but the result of many years of work to improve the enrichment technology.

How the diamond was found:
Ore preparation:

• Crushing to a specific size range;
• Classification to the -50+25 mm and -25+13 mm size ranges.

• X-rays (25-33 kV) excite diamond luminescence;
• Photodetectors detect the blue luminescence (wavelength from 330 to 600 nm with a maximum around 460 nm) specific for diamonds;
• Diamond bearing concentrate, including the unique stone, was passed to the next recovery stage.

Final retreatment at LS-OD-50-03N.

Diamond recovery became possible due to innovative technologies and modern equipment of Bourevestnik, JSC. 
Reference:https://www.alrosa.ru/press-center/news/2025/alrosa-dobyla-krupneyshiy-almaz...