Nickel prices slumped as much as 5.8 per cent to $13,185 a ton on the London Metal Exchange, retreating from two-year highs struck earlier in the week.
The sale of 4,170 carats of Lulo diamonds achieved gross proceeds of US$9.14 million (A$11.43 million), representing an average price per carat of US$2,192.
Jewellers in India had delayed purchases earlier this week and offered gold at a discount anticipating a reduction in the tax in the country's annual budget on Thursday.
Bankers, brokers, refiners and researchers in the London Bullion Market Association's 2018 survey sees gold as high as $1,510 and as low as $1,120 an ounce.
Rio’s renewed interest in SQM is welcome by the Chilean government, which had expressed concerns about a potential and dangerous concentration in the market should major lithium producers, such as China’s Tianqi, acquire the 32% interest in SQM.