Why is this a Carbon World?Your planet's carbon (22.1%) outweighs its oxygen (12.3%), so the mineralogy flips from silicate rock to carbide - a graphite crust over a diamond mantle.
Carbon worlds form in carbon-rich disks where there isn't enough oxygen to bind it all into silicates. Instead carbon condenses directly into graphite, carbides, and - under pressure at depth - diamond. They form water-poor, so no life takes hold.
Matched on physical properties only — no confirmed exoplanet orbits a black hole.Discovered 2017 via radial velocity · 19 light-years awaySource: NASA Exoplanet Archive