What is the most common crystal habit of gem diamond?

What is the most common crystal habit of gem diamond?

• A. The Cube
• B. The Octahedron
• C. The Prism
• D. The Dodecahedron

Answer: (B)

Diamonds grow in a cubic lattice, and the faces that end up defining most natural crystals are the {111} planes, which are the most densely packed and grow more slowly. An octahedron is bounded by six triangular faces that lie on these {111} planes, so a diamond crystal readily forms an octahedral shape as it grows. The cube would expose {100} faces, which in diamond are less stable or grow faster, making cube-shaped crystals far less common. Other shapes like prisms or dodecahedra require less typical combinations of crystal faces and are much rarer in gem-quality diamonds. So the octahedral habit is the most frequently observed form because it aligns with the fundamental growth directions and stability of the diamond crystal structure.

Diamonds grow in a cubic lattice, and the faces that end up defining most natural crystals are the {111} planes, which are the most densely packed and grow more slowly. An octahedron is bounded by six triangular faces that lie on these {111} planes, so a diamond crystal readily forms an octahedral shape as it grows. The cube would expose {100} faces, which in diamond are less stable or grow faster, making cube-shaped crystals far less common. Other shapes like prisms or dodecahedra require less typical combinations of crystal faces and are much rarer in gem-quality diamonds. So the octahedral habit is the most frequently observed form because it aligns with the fundamental growth directions and stability of the diamond crystal structure.