What Do Diamond Inclusions Look Like? A Visual Clarity Guide

Understanding Diamond Inclusions

Inclusions are internal characteristics that formed during diamond crystallization deep in the Earth's mantle. These natural features—minerals, fractures, growth patterns—are like fingerprints that prove a diamond's natural origin and make each stone unique.

GIA evaluates clarity by examining diamonds under 10x magnification and grading based on inclusion number, size, position, relief (contrast), and nature (type). The clarity scale ranges from Flawless (no inclusions visible at 10x) to I3 (inclusions obvious to naked eye).

Feathers: The Most Common Inclusion

Feathers are internal breaks or fractures in the diamond's crystal structure. They're called "feathers" because under magnification they resemble white, feathery patterns.

Visual Appearance

• Color: Usually white or transparent with feathery, wispy edges
• Pattern: Irregular branching patterns resembling bird feathers or frost on glass
• Visibility: Can range from barely visible wisps to prominent white clouds depending on size and angle

Durability Concerns

Feathers that reach the diamond's surface create potential durability issues. Surface-reaching feathers provide entry points for dirt and oil, and in severe cases, can create fracture risks if struck. Internal feathers (not reaching surface) generally don't affect durability.

Crystals: Mineral Inclusions

Crystals are mineral inclusions trapped inside the diamond during formation. They can be other diamonds, garnets, or various minerals.

Types of Crystals

• White Crystals: Tiny white or transparent spots; most common type; low contrast makes them less visible
• Black Crystals: Dark spots (usually carbon or graphite); high contrast makes them more visible and impactful
• Colored Crystals: Occasionally red (garnet) or other colors; rare

Black crystals have significantly higher visibility impact than white crystals due to contrast. Even small black crystals can be eye-visible in SI grades, while white crystals of similar size might remain eye-clean.

Clouds: Groups of Tiny Inclusions

Clouds are clusters of minuscule inclusions (often microscopic pinpoints) grouped together. They appear as hazy, whitish areas under magnification.

Impact on Diamond Appearance

Clouds are particularly concerning when they're:

• Dense and Large: Can reduce transparency and create milky appearance throughout diamond
• Centrally Located: Clouds under the table affect overall appearance more than edge clouds
• "Not Shown" on Plot: When GIA plots state "clouds not shown," it means clouds are so widespread they couldn't be plotted individually—often indicates transparency issues

Always view diamonds with clouds in person or through high-quality video. Photos alone cannot show transparency issues caused by dense clouds.

Pinpoints: Tiny Dot Inclusions

Pinpoints are extremely tiny white or black dots—essentially microscopic crystals. They're among the smallest inclusion types.

• Size: Microscopic; appear as tiny dots even at 10x magnification
• Impact: Individual pinpoints have minimal impact on clarity or appearance
• Clustered Pinpoints: When grouped together, can form clouds affecting transparency

Single pinpoints are often the grade-setting characteristic in VVS diamonds—barely visible at 10x magnification.

Needles: Linear Crystal Inclusions

Needles are long, thin crystal inclusions that appear as lines under magnification.

• Shape: Thin, elongated lines; can be straight or curved
• Color: Usually white or transparent; occasionally dark
• Visibility: Needles aligned with facets are less noticeable than needles cutting across multiple facets

Cavities: Surface Indentations

Cavities are openings on the diamond's surface where crystal or feather reached the surface and was removed or where surface chipped away.

Impact and Concerns

• Durability: Can collect dirt, oil, and debris; difficult to clean
• Further Damage: May catch on clothing or objects; potential weak points
• Appearance: High visibility due to surface location and shadow effects

Cavities are among the more undesirable inclusion types. Avoid SI diamonds with significant cavities as grade-setting characteristics.

Twinning Wisps: Growth Pattern Inclusions

Twinning wisps result from irregular crystal growth during diamond formation. They appear as wavy, ribbon-like patterns.

• Pattern: Wavy, ribbon-like formations with irregular borders
• Composition: Often complex combinations of clouds, feathers, and crystals
• Impact: Can range from minimal (faint wisps) to significant (prominent wisps reducing transparency)

Knots: Surface-Breaking Crystals

Knots are crystals that extend to the diamond's surface, creating a raised "bump" on a polished facet.

• Durability: Knot may dislodge if struck, creating cavity
• Polishing: Different mineral hardness affects how facet polishes; can create luster inconsistency
• Visibility: Surface location makes knots more noticeable than internal crystals

How Inclusions Affect Different Clarity Grades

Flawless (FL) and Internally Flawless (IF)

No internal inclusions visible at 10x magnification. IF may have insignificant surface blemishes.

VVS1-VVS2 (Very Very Slightly Included)

Minute inclusions extremely difficult to see at 10x:

• Tiny pinpoints requiring effort to locate
• Very faint needles or feathers

VS1-VS2 (Very Slightly Included)

Minor inclusions visible at 10x but difficult to see:

• Small crystals, feathers, or clouds
• Multiple pinpoints
• Nearly always eye-clean

SI1-SI2 (Slightly Included)

Noticeable inclusions at 10x; may be eye-visible in SI2:

• Larger crystals (white or black)
• More prominent feathers or clouds
• SI1 typically eye-clean; SI2 may show inclusions to naked eye

I1-I3 (Included)

Obvious inclusions visible to naked eye affecting transparency and brilliance:

• Large crystals, especially black
• Dense clouds creating milkiness
• Prominent feathers throughout stone