Diamond mines are often dangerous and deadly. In recent years, the routine sourcing of precious metals and minerals has been scrutinized for harming — and even killing — children, according to Human Rights Watch. As a result, jewelry companies have taken steps toward responsible sourcing. Tech giant International Business Machines Corp. wants to help. The the Armonk, New York-based company (NYSE: IBM) announced Thursday that it is collaborating with a team of companies to develop blockchain…