Leonardo DiCaprio

While he has yet to be spotted wearing lab-grown diamonds, Leonardo DiCaprio has become one of the biggest investors in the synthetic jewelry industry. After starring in the film Blood Diamond in 2006, a fictional thriller about the dangers of the diamond mining industry, DiCaprio became a vocal advocate for ethically sourced stones. In 2015, he invested in Diamond Foundry Inc., a San Francisco-based company that uses solar technology to produce lab-grown diamonds.