Some of the profit could have been spent on direct support for the Russian military Big brands like Tiffany and Cartier may mislead their clients by claiming they don't buy Russian diamonds, something they cannot guarantee, and thus make them unwitting supporters of the Russian war effort The biggest diamond companies in the world teamed up to allegedly jeopardize the authorities' attempts to close sanctions loopholes Soon after Russia launched its full-scale invasion of Ukraine, luxury brands like Tiffany and Cartier announced they had stopped buying Russian diamonds. An investigation by the Kyiv Independent has found evidence to the contrary.