G7 nations will ban imports of Russian diamonds from January 1 and implement staged embargoes on trading the stones throughout 2024, under an agreement aimed at restricting one of the few leading Russian exports still untouched by western sanctions.

The deal, set to be announced on Wednesday by the group of wealthy nations, follows months of wrangling between western capitals over how such a ban would work, and widespread concern from big African diamond producers that the measures could hurt their trade in the precious stones.

The diamond ban is a welcome sign of support from western allies as Ukraine has recently become increasingly anguished by the failure of the EU and the US to commit to long-term financial and military support and as its counteroffensive against Russian troops has largely failed to make significant gains on the ground.