How to identify Diamond

To correctly identify Diamond (C (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

   Colorless, yellow, brown, green, blue, pink, red, orange, black. The most prized are colorless, but fancy colors are also highly valued.

2. 2

   Luster

   How the surface reflects light: metallic, vitreous, dull

   Adamantine (brilliant, diamond-like).

3. 3

   Texture

   Grain size and surface feel: coarse, fine, glassy

   Smooth to slightly rough on natural crystal faces; fractured surfaces are conchoidal.

4. 4

   Crystal Form

   Shape of visible crystals or crystal faces

   Typically octahedral, dodecahedral, or cubic. Often found as euhedral crystals, but also as irregular fragments or bort (industrial-grade diamonds with poor crystal structure).

5. 5

   Cleavage

   How it breaks: flat cleavage planes vs irregular fracture

   Perfect in four directions (octahedral), which can be exploited for cutting but also makes them susceptible to fracture along these planes.

6. 6

   Geological Environment

   The rock formation and setting where it occurs

   Primary deposits are kimberlite and lamproite pipes. Secondary (alluvial) deposits are found in riverbeds and coastal areas where diamonds have been eroded from their primary sources and transported.

Key Facts

Hardness

10 (Mohs scale), the hardest known natural mineral.

Specific Gravity

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

Crystal System

Isometric (cubic).

Color

Colorless, yellow, brown, green, blue, pink, red, orange, black. Can be transparent, translucent, or opaque.

Luster

Adamantine.

Transparency

Transparent to opaque.

Fracture

Conchoidal to uneven.

Cleavage

Perfect in four directions (octahedral).

Composition

Pure carbon (C).

Physical characteristics

• Crystal Habit: Octahedral, dodecahedral, cubic, or combinations thereof. Also massive (bort, carbonado).
• Cleavage Type: Perfect octahedral {111}.
• Fracture Type: Conchoidal to uneven.
• Tenacity: Brittle, despite its hardness, it can be fractured along cleavage planes or by sharp impact.
• Luster Type: Adamantine.

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