Surface Features

Introduction

Surface features are characteristics found at or near the surface of gemstones.
While strictly speaking not "inclusions" (which are internal), these features
are often considered together in gem examination and significantly impact
clarity grading, particularly in diamonds.

Naturals

Naturals are remnants of the original crystal surface left on a cut gemstone:

Characteristics:

Original rough crystal surface preserved
Usually found on or near the girdle
May show trigons (triangular growth marks)
Often left deliberately to preserve weight

Significance:

Proves natural origin (synthetics don't have naturals)
Acceptable in diamond grading if confined to girdle
Should not affect face-up appearance

Types of Naturals

Type	Description	Location
Surface natural	Flat area of original surface	Girdle area
Indented natural	Extends below polished surface	Girdle or near
Natural with trigons	Shows triangular growth marks	Any natural surface
Twinning natural	Related to twin plane	Follows twin orientation

Bearding (Girdle Fringes)

Bearding consists of tiny fractures along the girdle, created during cutting:

Formation:

Created by the bruting (girdling) process
Mechanical stress causes minute fractures
Extends from girdle into stone interior

Appearance:

Hair-like fractures at girdle edge
Creates "fuzzy" or "fringed" appearance
Severity ranges from minor to extensive

Grading impact:

Minor bearding often acceptable
Heavy bearding can affect clarity grade
May be reduced by re-polishing girdle

Extra Facets

Extra facets are small additional polished surfaces not part of the standard cut:

Purposes:

Remove surface-reaching inclusions
Eliminate naturals or damage
Correct cutting errors

Location:

Often on pavilion near girdle
May be on crown
Should not be visible face-up (ideally)

Grading consideration:

Generally considered a blemish
Impact depends on visibility
Very common in coloured stones

Surface Graining

Surface graining appears as visible growth lines on polished surfaces:

Types:

Whitish graining - Light-coloured lines
Reflective graining - Shiny, mirror-like lines
Transparent graining - Subtle lines, often internal origin

Relationship to internal graining:

Surface graining often continues internally
Represents structural irregularities
Related to crystal growth conditions

Etch Channels and Figures

Etch features result from natural dissolution processes:

Etch channels:

Tube-like cavities extending from surface
Created by corrosive fluids during geological history
Often follow crystallographic directions
Can contain secondary minerals

Etch figures:

Geometric depressions on crystal faces
Reflect underlying crystal symmetry
Trigons on diamond (triangular pits)
Hexagonal pits on corundum

Trigons on Diamond

Pits and Cavities

Feature	Description	Cause
Pit	Small, shallow depression	Pulled-out inclusion
Cavity	Angular void, often geometric	Removed crystal inclusion
Chip	Shallow break at facet junction	Mechanical damage
Nick	Small chip at facet edge	Wear or damage
Scratch	Linear surface mark	Abrasion damage

Laser Drill Holes

Laser drilling is a treatment that creates access channels to internal inclusions:

Purpose:

Access dark inclusions for bleaching
Improve apparent clarity

Appearance:

Very fine, straight channels
May appear as tiny dots on surface
Often lead to bleached inclusion sites
Visible under magnification

Detection:

Look for unnaturally straight tubes
Follow tube to inclusion site
May show surface opening