Four large rough diamonds have “disappeared” while in the custody of Russia’s State Precious Metals and Gems Repository, better known as Gokhran, said reports in the country’s media.

The diamonds were part of a consignment of reportedly 150,000 carats handed over to Gokhran to be kept as inventory by Severalmaz, a subsidiary of Alrosa.

Unidentified industry sources told Kommersant, a Russian daily newspaper that after the diamonds were sorted, some of them were replaced with inferior ones while four large ones went missing altogether. One of these missing ones is said to be over 23 carats. It is also reported that the missing diamonds were insured for US$ 500,000. Trade analysts say that their actual market value could be substantially more.

An investigation has been ordered into the matter and a state commission has been set up to do so, it is reported.

Gokhran, Russia’s state repository has since it was set up in 1920 has been the custodian of the country’s precious metals and precious  gemstones.