While the council’s best-known members are major brands and businesses, Ms. Grant said independent jewelers might hear from her about joining the council to help combat issues like pollution and climate change. “Even if you’re an artist in a cave, crafting something in seclusion, eventually they’re going to affect you,” she said, referring to those global challenges. “There are practical things we can do as an organization to help people look at their practice and how they can contribute.”

She said she did plan to be realistic about her expectations: “It’s not a fast-moving industry. It’s old but it’s not fast. The challenge is navigating all the opinions and the views with the reality of what’s possible.”

Over time, the council, like other industry players espousing sustainability standards, has faced critics who accused it of greenwashing and setting lenient standards. Last year, after Russia’s invasion of Ukraine, many of the R.J.C.’s own members were displeased the council did not expel the diamond giant Alrosa, which is owned partly by the Russian government. That inaction led to the departure of some high-profile members, including Richemont, the owner of brands such as Cartier, and Pandora, the world’s largest jewelry company by volume.

In April 2022, the R.J.C. board voted to accept Alrosa’s decision to suspend its membership, the status it still holds today. A majority of the departed members, including Richemont, returned to the council, though Pandora did not.

Ultimately, such frictions are inevitable and “healthy,” Paul Zimnisky, an independent diamond industry analyst based in New York, said in a phone interview. “They keep international organizations like R.J.C. on their toes.” Mr. Zimnisky later noted that, with a membership that spanned “different cultures, different religions, different economic circumstances and different political ideologies, coming to a consensus on anything is understandably difficult.”

Transparency, he said, is one of the main benefits that groups such as the council can offer. “They can really add value by providing consumers with reliable information and letting the consumers decide.”