Akoya and other saltwater pearls are more common than natural, non-cultured pearls, and make up about 5% of all those sold. These types are high quality and meant to last for decades with moderate use and the proper care. They are often passed on to future generations! Pearls are very susceptible to pollution; therefore, pearl farmers are often environmentalists. Tiffany, “when possible", sources directly from suppliers and pearl farmers that share their beliefs on environmental stewardship. Unfortunately, I was unable to find further information on what how often this is "possible".
Tiffany only accepts diamonds that originate in countries without diamond-related human rights concerns, and actually, since 2019, one can make an appointment through their Diamond Source Initiative to determine the origin of your diamond. Similarly, 98% of the gold used in their internally manufactured products are sourced from the company’s two mines and two refiners.
This transparency is what really gets this product a planet in this category.
The packaging is about 84% sustainably sourced, meaning they fall under the "Best" category (FSC-certified to the highest tier) or "Better" (fiber form controlled sources, PEFC-certified, content originally certified, reclaimed/recycled/repurposed). This includes the infamous Tiffany Blue Box. They work closely with the Rainforest Alliance and have a "strong preference" that 100% of paper suppliers of Tiffany Blue Boxes and bags in 2013 were FSC-certified. This certification, however, has been criticized for greenwashing illegal logging and not really halting deforestation.
I haven't been able to find a sustainability report since 2017, which raises some concern, but they do have a fair amount of information on their website.
Tiffany boasts being a leader in the industry when it comes to sustainability, and they are, that’s one of the reasons LVMH acquired them! They received a “Strong” ranking for responsible sourcing of diamonds and gold from Human Rights Watch—the only jeweler to earn this designation.
But, as an industry leader, Tiffany still has considerable ways to go.