Octahedral Crystals (15.08)
The most sought-after rough specimens are well-formed octahedral crystals in larger sizes (2.00 to 20.00 carat sizes) with white, eye-clean qualities. The eight-sided octahedral rough crystal in its ideal shape, would look like two pyramids joined at the bases in natural diamond. Even though all diamonds fall into the cubic system category, not all rough will have similar shapes (discussed in subsection #3.02). Every natural diamond, regardless of its appearance, contains twelve single grains running in their predetermined directions. Like all other gemstones (or people for that matter), no two diamonds will ever be alike. The shapes come in almost every imaginable form, with a size range from small particles to small potato sizes.
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Note: Trigons also form on spinel crystals and superficially on quartz crystals.