WHAT IS SUSTAINABLE GOLD AND WHICH BRANDS ARE USING IT?

Eco-Friendly gold is slightly different. This gold is mined in such a way to ensure minimal impact on the land and environment - for example, no toxic chemicals are used during the process. Most large-scale mining companies use mercury (which is a major pollutant) to recover the gold, 
read more... https://www.euronews.com/living/2019/08/03/what-is-sustainable-gold-and-which-brands-are-using-it.