Exquisitely Ethical Mpingo: Pitch black, rock hard and the price of gold - our sustainably sourced mpingo blackwood is both beautiful and ethical. Wanting to avoid mined diamonds, we found that this rare natural material can be cut precisely like a diamond, while causing no harm in the world. Our mpingo is sourced from a sustainable, WWF-protected project in Tanzania. In fact, we use only leftover pieces from a sustainable clarinet production. Worn next to your skin, mpingo will grow ever more beautiful over time.