Human rights and environmental advocates have tried to reform the diamond mining industry, but what if the answer was as simple as just growing diamonds in a lab? That’s what start-ups like Ada Diamonds are betting on. They sell lab-grown diamond jewelry that’s molecularly identical to naturally-formed diamonds, but for only two-thirds the price. In fact, the FTC just changed its definition of “diamond” to make it clear that lab-grown diamonds are indeed real diamonds, and that companies like Ada can market them as “cultured diamonds.”

Hear from Joe in this new interview about his journey from working at Ferari to founding a guitar company to now founding and running a company whose goal is, just like Dr. Seuss’s Lorax, nothing short of saving the trees.

Toilets drastically improve health, life expectancy, school attendance rates, and more. And this episode, we’ve got someone who says every trip you make to the toilet can be a feel-good experience–since the company Simon Griffiths started, Who Gives a Crap, was founded for one reason: to give people in the developed world toilets.

His Royal Highness Prince Khaled bin Alwaleed bin Talal isn’t your typical vegan. A son of the man TIME magazine calls the “Arabian Warren Buffett,” he uses his wealth and influence to build a more sustainable world, supporting everything from plant-based and clean meat start-ups to virtual aquariums and clean energy.

Black pollution is the new green in India, as Bharti Singhla points out in this episode. A chemical engineer, Bharti’s the executive vice president of strategy for Chakr.in–a start-up founded in 2015 that’s innovating a way to clear the air in a nation that according to the WHO has 14 of the 15 most polluted cities on the planet.