Which diamond plane is most efficient for sawing and dividing large, regularly shaped crystals?

• A. Octahedral planes
• B. Cubic planes
• C. Dodecahedral planes
• D. Trigonal planes

Answer: (B)

The idea is that bulk sawing works best when you cut along the crystal’s broad, regular faces rather than along its natural planes of weakness. For diamond’s cubic crystal system, the cube faces provide large, flat, straight surfaces that can be removed efficiently with minimal waste. Cutting along these cubic planes lets you divide a large, well-formed crystal into sizable, manageable pieces cleanly and predictably.

In contrast, octahedral planes are planes of cleavage—the crystal tends to split along them rather than cut cleanly, which makes sawing risky and less efficient. The other plane sets aren’t the primary, straightforward faces you rely on for bulk reduction of a regularly shaped crystal, so they aren’t as suitable for efficient sawing.