Identify the term used for a well formed diamond crystal that is octahedral and transparent with sharp, square edges.

Identify the term used for a well formed diamond crystal that is octahedral and transparent with sharp, square edges.

• A. Crystal
• B. Glassie
• C. Crystal Systems
• D. Doubling

Answer: (B)

The term is crystal. A well-formed diamond crystal is a single, natural piece that has grown with clean, well-defined faces—the octahedral habit is a classic shape diamonds often exhibit because of their cubic lattice. Such a crystal appears transparent with crisp, sharp edges where faces meet. Terms like glassie aren’t standard in gemology for describing a well-formed diamond; a glassy texture would imply a non-crystalline material, not a proper diamond crystal. Crystal Systems refers to how crystals are classified by symmetry, not the appearance of a single crystal, and Doubling relates to optical birefringence, which diamonds do not show. So the best description for that well-formed piece is a crystal.

The term is crystal. A well-formed diamond crystal is a single, natural piece that has grown with clean, well-defined faces—the octahedral habit is a classic shape diamonds often exhibit because of their cubic lattice. Such a crystal appears transparent with crisp, sharp edges where faces meet. Terms like glassie aren’t standard in gemology for describing a well-formed diamond; a glassy texture would imply a non-crystalline material, not a proper diamond crystal. Crystal Systems refers to how crystals are classified by symmetry, not the appearance of a single crystal, and Doubling relates to optical birefringence, which diamonds do not show. So the best description for that well-formed piece is a crystal.