How to identify Yellow Diamond

To correctly identify Yellow Diamond (Diamond (C)), 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

   Ranges from faint yellow to light yellow, fancy light yellow, fancy yellow, fancy intense yellow, fancy vivid yellow, and fancy deep yellow. The color is typically uniform.

2. 2

   Luster

   How the surface reflects light: metallic, vitreous, dull

   Adamantine (diamond-like), exceptionally brilliant.

3. 3

   Texture

   Grain size and surface feel: coarse, fine, glassy

   Smooth to the touch when polished; rough diamonds may have a greasy feel.

4. 4

   Crystal Form

   Shape of visible crystals or crystal faces

   Typically forms in isometric crystal habits, most commonly octahedra, dodecahedra, and cubes, or combinations thereof. Macles (twinned crystals) are also common.

5. 5

   Cleavage

   How it breaks: flat cleavage planes vs irregular fracture

   Perfect octahedral cleavage in four directions, meaning it can be split along specific planes parallel to the faces of an octahedron.

6. 6

   Geological Environment

   The rock formation and setting where it occurs

   Found in kimberlite and lamproite pipes, which are volcanic conduits that brought diamonds from the Earth's mantle to the surface. Also found in secondary alluvial deposits, where diamonds have been eroded from their primary sources and transported by rivers.

Key Facts

Hardness

10 on the Mohs scale (hardest known natural mineral)

Specific Gravity

3.50 - 3.53 g/cm³

Crystal System

Isometric (Cubic)

Color

Faint yellow to vivid fancy yellow, caused by nitrogen impurities.

Luster

Adamantine

Transparency

Transparent to translucent

Fracture

Conchoidal to uneven

Cleavage

Perfect octahedral in four directions {111}

Composition

Pure carbon (C), with trace amounts of nitrogen causing the yellow color.

Physical characteristics

• Crystal Habit: Octahedral, dodecahedral, cubic, or combinations; also macles (twinned crystals) and irregular shapes.
• Cleavage Type: Perfect octahedral {111}
• Fracture Type: Conchoidal to uneven
• Tenacity: Brittle (despite extreme hardness, it can be fractured along cleavage planes or by sharp impact)
• Luster Type: Adamantine

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