The 555.55 carat black diamond has belonged to its current owner for two decades but little is known about its history before that. A billion-year-old black diamond, believed to be the world's ...

In the '80s and '90s, gem-quality brown diamonds were worth about $1,500 per carat ... lack of supply driving up the price. Black opal costs from $1,000 a carat to tens of thousands of dollars.

The 555.55 carat black diamond has belonged to its current owner for two decades but little is known about its history before that. A billion-year-old black diamond, believed to be the largest cut ...

Analyst Robert Burns of H.C. Wainwright reiterated a Buy rating on Black Diamond Therapeutics (BDTX – Research Report), retaining the ...