Company also forced to close key mine amid ongoing dispute with government over how the precious stones are valued. Petra Diamonds’ stock market value fell after the Tanzanian government seized a parcel of gems valued at nearly $15m (£11.4m) as part of a parliamentary investigation into alleged wrongdoing in the diamond sector.
The London-listed company also had to shut down its Williamson mine, the source of the stones, as “certain key personnel” were questioned by the Tanzanian authorities looking into how diamonds are being valued.
Shares in the company, which said it had not been made “formally aware” of the reason for the investigation, fell nearly 25% when the market opened, before recovering to settle at about 6% lower, down 6.2p at 83.75p.
The diamonds were confiscated at Dar es Salaam airport on 31 August as they were being readied for export to Antwerp, with Tanzanian officials claiming they had been undervalued.
“While Williamson Diamonds declared in its documentation that the value of the diamonds was $14.798m, a fresh valuation done by the government established that the actual value of the diamonds is $29.5m,” the finance ministry said in a statement.
“Among the legal action to be taken include the nationalisation of all the diamonds seized after it was established that there was cheating involved in declaring the actual value of the minerals.”