The transparency initiative is aimed at stemming the flow of so-called ‘blood' or 'conflict' diamonds in the retail market and is positioned to impose more stringent transparency parameters than the existing Kimberley Process, an initiative launched by the United Nations in 2003 to prevent conflict diamonds from entering mainstream markets.

Starting immediately, Tiffany will provide sourcing information for diamonds 0.18 carats and larger and will in 2020 share more information about the "craftsmanship" journey of the precious gems, such as cutting and polishing workshop location.

"Diamonds, formed up to three billion years ago and brought to the earth's surface by a miracle of nature, are symbols of the most important moments in our lives," said Tiffany CEO Alessandro Bogliolo. "There should be nothing opaque about Tiffany diamonds."

In cases where a diamond's provenance is unknown, such as with stones that predate the policy, Tiffany will assure that the diamond was sourced with industry leading practices, the company said.

Human Rights Watch welcomed the announcement after it had last year launched the #BehindtheBling campaign to pressure jewellery companies to be more transparent.

The non-profit's advocacy director Jo Becker said diamonds might be tainted by other abuses, including displacement, forced or child labour and environmental harm.

According to the US Department of Labour, for example, diamonds from seven African countries may be mined with child or forced labour. Diamonds from Zimbabwe may be linked to torture, beatings, harassment, and forced relocation.

"Tiffany's announcement is another step forward, and we encourage others, particularly diamond mining companies, to provide their clients with information on the origins of the diamonds they sell," Becker said.

Going forward, polished stones will be required to comply with Tiffany's ‘Diamond Source Warranty Protocol', which restricts sourcing to countries that do not present diamond-related human rights concerns.

Stones from responsibly managed mines in Canada, Botswana, Namibia, or South Africa will be designated ‘Botswana sort.' Heritage gems that were sourced before the initiative launched will have their sourcing practices certified by Tiffany.

"Tiffany & Co has long been committed to diamond traceability and going above and beyond industry norms to promote the protection of the environment and human rights," said Tiffany's chief sustainability officer Anisa Kamadoli Costa. "A transparent journey of responsible sourcing reflects the many positive and far-reaching benefits along every step of the diamond supply chain."