How to identify Diamond

To correctly identify Diamond (Carbon), check each of these features in order. Many rocks and minerals look alike, so cross-reference multiple properties before deciding.

Step-by-step identification

1. 1

   Color

   Overall color and any zoning or banding

   Typically colorless to pale yellow or brown, but can occur in nearly any color (fancy colors) due to impurities or structural defects. Common colors include yellow, brown, green, blue, pink, red, and black.

2. 2

   Luster

   How the surface reflects light: metallic, vitreous, dull

   Adamantine (diamond-like), exceptionally bright and reflective.

3. 3

   Texture

   Grain size and surface feel: coarse, fine, glassy

   Rough, often greasy or waxy on unpolished surfaces; polished surfaces are extremely smooth.

4. 4

   Crystal Form

   Shape of visible crystals or crystal faces

   Cubic system, commonly found as octahedra, dodecahedra, cubes, or combinations thereof. Macles (twinned crystals) are also common. Often exhibits trigons (triangular growth marks) on octahedral faces.

5. 5

   Cleavage

   How it breaks: flat cleavage planes vs irregular fracture

   Perfect octahedral cleavage in four directions. This means it can be split along specific planes, despite its extreme hardness.

6. 6

   Geological Environment

   The rock formation and setting where it occurs

   Primarily found in kimberlite and lamproite pipes (volcanic conduits) that originate in the Earth's mantle. Also found in alluvial (placer) deposits, which are secondary deposits formed by the erosion and transport of primary kimberlite/lamproite sources.

Key Facts

Hardness

10 (Mohs scale), the hardest natural mineral.

Specific Gravity

3.50 - 3.53 g/cm³ (varies slightly with impurities).

Crystal System

Cubic (isometric).

Color

Colorless, yellow, brown, green, blue, pink, red, black, and other fancy colors.

Luster

Adamantine.

Transparency

Transparent to opaque.

Fracture

Conchoidal to uneven.

Cleavage

Perfect octahedral in four directions.

Composition

Pure carbon (C).

Physical characteristics

• Crystal Habit: Octahedral, dodecahedral, cubic, or combinations; often rounded or distorted; also massive (bort) or radiating (carbonado).
• Cleavage Type: Perfect, octahedral {111}.
• Fracture Type: Conchoidal to uneven.
• Tenacity: Brittle (despite extreme hardness, it can be fractured or cleaved by impact).
• Luster Type: Adamantine.

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