Chapter 9 Flashcards
1
Q
What year were workers at South Africa’s Premier mine surprised by a diamond jamming the machinery?
A
1977
2
Q
What was the weight of the rough diamond that jammed the machinery in Premier mine in 1977?
A
353.90 ct.
3
Q
What three diamonds were cut from the rough diamond at the Mouw Diamond Cutting Works?
A
- 137.02 ct. Premier Rose
- 31.48 ct. Little Rose
- 2.11 ct. Baby Rose
4
Q
What grading did the GIA laboratory assign to all three Rose diamonds?
A
D-Flawless
5
Q
What is one of the most important aspects of the GIA diamond grading system?
A
Clarity grading
6
Q
What are clarity characteristics often referred to as by customers and some jewelers?
A
Flaws or imperfections
7
Q
What purposes do clarity characteristics serve about a diamond?
A
- Clarity grade
- Value
- Identification
8
Q
What are the two types of clarity characteristics?
A
- Inclusions
- Blemishes
9
Q
What do inclusions refer to in terms of clarity characteristics?
A
Features enclosed within a gemstone or extending into it from the surface
10
Q
What do blemishes refer to in terms of clarity characteristics?
A
External features confined to a gemstone’s surface
11
Q
What factors affect a diamond’s clarity grade in the GIA system?
A
- Number
- Size
- Location
- Relief
- Nature of characteristics
12
Q
How do graders determine the clarity grade of a diamond?
A
By finding clarity characteristics and judging their visibility at 10x magnification
13
Q
What is the recommended magnification for examining diamonds?
A
10x
14
Q
What tools are recommended for clarity grading?
A
- 10x triplet loupe
- Gemological microscope
15
Q
What is chromatic aberration?
A
Color distortion causing a rainbow effect around the viewing field
16
Q
What is spherical aberration?
A
Linear distortion causing straight lines to appear bent at the edges
17
Q
What type of lenses are corrected for color distortion?
A
Achromatic lenses
18
Q
What type of lenses are corrected for spherical aberrations?
A
Aplanatic lenses
19
Q
What is the importance of keeping a diamond clean before examination?
A
To avoid smudges and dust that can affect clarity grading
20
Q
What is a recommended way to hold a diamond during examination?
A
With tweezers to avoid skin oils
21
Q
What can bright light reflected off a facet help to identify?
A
Surface-reaching inclusions
22
Q
True or False: A grade can usually be assigned without naming every inclusion.
A
True
23
Q
Fill in the blank: Clarity grading begins with locating what gemologists call _______.
A
clarity characteristics
24
Q
What do corrected loupe lenses eliminate?
A
Distortions
They are important for viewing small details in gemstones.
25
What are achromatic lenses corrected for?
Color
## Footnote
They help in reducing color distortions.
26
What are aplanatic lenses corrected for?
Spherical aberrations
## Footnote
This correction improves image clarity.
27
What are two tools used for clarity grading?
10x triplet loupe and gemological microscope
## Footnote
Each tool has advantages for different situations.
28
What is one advantage of using a loupe?
Portability
## Footnote
It is also affordable.
29
What is one advantage of using a microscope?
Stability and adjustable magnification
## Footnote
It is easier to locate and identify characteristics.
30
Where is a microscope most useful?
In a store or office
## Footnote
It is less portable than a loupe.
31
What should you base a diamond’s clarity grade on?
Appearance in a 10x loupe
## Footnote
Even if using a microscope to find characteristics.
32
What is extremely important before examining a diamond?
Keeping the diamond as clean as possible
## Footnote
Use a pointer and lint-free cloth.
33
How should you hold the diamond to avoid skin oils?
With tweezers
## Footnote
This prevents contamination from handling.
34
What is a good technique to stabilize the loupe and tweezers?
Rest elbows on a table or brace against sides
## Footnote
This helps steady your hands.
35
How should you hold the tweezers when using a microscope?
Rest them on the microscope’s stage
## Footnote
This provides stability while examining the diamond.
36
What can a pointer help distinguish?
Dust or lint from pinpoints or scratches
## Footnote
It aids in identifying inclusions.
37
What can bright light reflected off a facet help identify?
Surface-reaching inclusions
## Footnote
It is a helpful technique for examination.
38
What is darkfield illumination used for?
To search for and examine clarity characteristics of diamonds
## Footnote
Darkfield illumination lights the diamond from the side against a black non-reflective background
39
How does darkfield illumination affect the visibility of inclusions in diamonds?
It causes inclusions to stand out as bright objects against a dark background
## Footnote
This method allows for the viewing of most inclusions within the diamond
40
What type of illumination is created by illuminating the diamond from below?
Brightfield illumination
## Footnote
In this method, inclusions appear as dark objects against a bright background
41
How can brightfield illumination be achieved when examining a diamond?
By tilting the diamond until light reflects off the opposing facet’s surface
## Footnote
This technique enhances the visibility of inclusions
42
What is the likelihood of encountering Flawless diamonds?
It is unlikely unless you are a wholesaler or a retailer specializing in them
## Footnote
Most diamonds contain inclusions
43
What is important to do when examining diamonds for inclusions and blemishes?
Approach the task in a consistent and systematic way
## Footnote
Being thorough and inspecting every part of the diamond is also crucial
44
What technique should be used to inspect a diamond’s interior?
Rock the diamond so the light source is perpendicular to a facet
## Footnote
This allows viewing into the stone as if looking through a window
45
How should you tilt the diamond to examine its surface?
Tilt it so the light reflects off the surface as if it were a mirror
## Footnote
This helps in assessing the surface characteristics
46
What method do clarity graders use to examine diamonds?
They divide the diamond into wedges, or pie slices, and examine one wedge at a time
## Footnote
This systematic examination helps ensure thorough inspection
47
What is the term for the distance above and below a focused point that remains clear and sharp?
Depth of field
48
How does increasing magnification affect the depth of field?
It gets shallower
49
What does it indicate if a characteristic is in focus while the surface is out of focus?
The characteristic is an inclusion within the stone
50
What does it indicate if both the surface and the characteristic are in focus?
It's a blemish or an inclusion that extends in from the surface or a totally enclosed inclusion just under the surface
51
How can you distinguish between surface and totally enclosed characteristics using light?
Position the stone so the light source is at an angle to the facet
52
What happens to the reflection of surface characteristics when light reflects off the facet?
They stand out while reflections mask almost everything within the stone
53
How can you determine how deep an inclusion lies within a diamond?
Look for its mirror reflection
54
What does it mean if the inclusion and its reflection appear to touch?
The inclusion extends into the stone from the surface
55
What can cause confusion regarding the number of inclusions seen?
Reflections of the same inclusion
56
How can you verify if multiple inclusions are actually reflections of the same inclusion?
Look at the inclusion from another direction
57
What is one indicator that multiple 'inclusions' are reflections?
They look identical
58
What phenomenon in diamonds causes you to see two or more images of the same characteristic?
Prism images
59
What is important for grading clarity when viewing a diamond?
Reflections that appear when you view the stone face-up
60
What are the two categories of inclusions in diamonds?
Internal and surface-reaching
## Footnote
Internal inclusions are totally enclosed within the diamond, while surface-reaching inclusions extend into the stone from the surface.
61
What can cause inclusions in diamonds?
Inclusions can be introduced during:
* Formation
* Manufacturing process
* Damage after fashioning
* Laser treatment
62
What is a crystal (Xtl) in the context of diamonds?
A mineral crystal contained in a diamond
63
How many different mineral crystals have researchers identified in diamonds?
More than 24 different mineral crystals
64
What are the most common types of crystals found in diamonds?
Smaller diamond crystals, olivine, and occasionally garnet crystals
65
True or False: Inclusions can only be introduced during the formation of a diamond.
False
## Footnote
Inclusions can also occur during manufacturing, from damage, or through laser treatment.
66
Fill in the blank: Inclusions might also be introduced by _______ during treatment.
lasers
67
What is the significance of the abbreviations used for diamond characteristics?
They are accepted throughout the industry for quick reference.
68
69
70
71
What term do some people use to refer to dark crystals?
Carbon spots
## Footnote
This term is considered incorrect and misleading.
72
What is required to determine the composition of dark crystals?
Complex laboratory equipment
## Footnote
Without this equipment, it's impossible to ascertain if they are made of carbon or another substance.
73
Name the inclusion type
XTL - crystal inclusion
74
Name the inclusion type
XTL
75
Name the inclusion type
XTL garnet crystal
76
Name the inclusion type
XTL grayish blue omphacite and pyrope-almandine
77
Name inclusion type
XTL crystal
78
Name the inclusion type
Ndl Needle
79
Name the inclusion type
PP pinpoints
80
Name the inclusion type
(Cld) Cloud
81
Name the inclusion type
(Cld) Cloud
82
What can usually be seen under high magnification in included crystals?
The flat faces and angular outlines of the inclusion’s crystal form.
83
How does lighting affect the appearance of included crystals?
Under darkfield illumination, they appear bright against a dark background; in brightfield, they often look black against a bright background.
84
What is a needle (Ndl) in the context of crystals?
A long, thin crystal that looks like a tiny rod at 10x magnification.
85
What color appearances can a needle (Ndl) have?
White, bright, or dark.
86
What is a pinpoint (Pp) in crystal terminology?
A very small crystal that looks like a tiny dot at 10x.
87
What is the most common color of pinpoints (Pp)?
White.
88
True or False: Pinpoints (Pp) can occasionally be dark.
True.
89
What is a cloud (Cld) composed of?
Many tightly grouped pinpoints
90
At what magnification might pinpoints in a cloud be too small to distinguish individually?
10x
91
How do clouds appear visually?
Like misty white or gray patches, or tiny flecks of white powder
92
What are the two main characteristics of clouds mentioned?
Size and density
93
How can a large and dense cloud affect a diamond?
It can reduce a diamond’s transparency and therefore its brilliance and beauty
94
True or False: Some clouds look like a light haze.
True
95
Fill in the blank: A cloud can look like _______ when it is dense.
a light haze
96
What effect does a cloud have on the beauty of a diamond?
It can reduce its brilliance and beauty
97
What is a twinning wisp (TW)?
A series of pinpoints, clouds, or crystals that forms in a twinning plane
## Footnote
Twinning wisps appear flat and ribbon-like and usually radiate out from the diamond’s center.
98
What causes internal graining (IG) in crystals?
Irregularities in crystal growth
## Footnote
Internal graining can affect the appearance and transparency of the stone.
99
How can internal graining (IG) appear?
It can take the form of lines or angles, and may be transparent, whitish, colored, or reflective
## Footnote
It might give part or all of the stone a hazy texture.
100
What texture might internal graining (IG) give to a stone?
A hazy texture
## Footnote
It can affect the transparency of the stone at 10x magnification.
101
What are some visual characteristics of internal graining (IG)?
It might look like a thin sheet of reflective plastic, fine white or colored streaks, falling rain or sleet, or vinegar in oil
## Footnote
Internal graining that appears colorless or transparent has no effect on the clarity grade.
102
What effect does colorless or transparent internal graining have on clarity grade?
It has no effect on the clarity grade
## Footnote
This means that such internal graining does not detract from the perceived quality of the stone.
103
What is a characteristic appearance of twinning wisps?
They can appear flat and ribbon-like
## Footnote
Twinning wisps are often easy to see in twinned crystals.
104
True or False: Twinning wisps can be found in single crystals.
False
## Footnote
Twinned crystals often display twinning wisps.
105
Name the inclusion
TW twinning wisp
106
Name the inclusion
TW twinning wisp
107
Name the inclusion
IG internal graining
108
Name the inclusion
IG internal graining
109
Name the inclusion
GC Grain Center
110
What is a grain center (GC)?
A type of internal graining consisting of a small concentrated area of crystal growth distortion
## Footnote
Grain centers can be white or dark and may appear thread-like or pinpoint-like.
111
How can grain centers appear within a diamond?
They can look like transparent tornadoes caught deep inside the diamond and may occur alone or in groups
## Footnote
Grain centers are not visible from all directions.
112
What are surface-reaching inclusions?
Inclusions that reach or touch the surface of a fashioned diamond or extend from the surface into the stone
## Footnote
These inclusions can affect the clarity and appearance of the diamond.
113
What is a feather (Ftr) in diamond terminology?
A general term for any break in a diamond
## Footnote
Known as a gletz in many countries.
114
What is cleavage in the context of diamonds?
A break that occurs in a cleavage plane—a planar surface along which a mineral tends to break due to atomic weakness
## Footnote
Cleavage breaks are specific to the crystal structure.
115
What is a fracture in diamond terminology?
A break in any other crystal direction that is not along a cleavage plane
## Footnote
Fractures can vary in appearance compared to cleavages.
116
How might a feather appear visually?
It might look shiny and white, glossy, or transparent, depending on the viewing direction
## Footnote
Some feathers can catch light and appear to blink from transparent to bright.
117
Name inclusion
Ftr (glossy)
118
Name inclusion
Ftr (white)
119
Name inclusion
Ftr (semitransparent)
120
Name inclusion
Etch channels
121
What is an etch channel (EC)?
An angular opening that starts at the surface of the diamond and extends into it
## Footnote
It can be straight or curved, shallow or deep, often with striations perpendicular to its length.
122
How does an etch channel (EC) occur?
It is thought to occur when something etches or chemically erodes rough diamonds as they travel to the earth’s surface
## Footnote
This process may involve natural elements that act upon the diamonds.
123
What is a bearded girdle (BG)?
Consists of minute or minor feathers running perpendicular to a bruted girdle
## Footnote
It can vary in appearance from lightly to heavily bearded.
124
What characterizes a lightly bearded girdle?
Has a few very fine feathers scattered around the diamond’s perimeter
## Footnote
These feathers are subtle and not overly pronounced.
125
What characterizes a heavily bearded girdle?
Has so many feathers that they create a fuzzy gray fringe all the way around the stone
## Footnote
This significant feathering is more noticeable than in a lightly bearded girdle.
126
How is a bearded girdle referred to in a GIA report?
Referred to in more general terms as feathers in the girdle
## Footnote
This terminology provides a broader category for the observed features.
127
Name the inclusion
BG Bearded Girdle
128
Name the inclusion
BG Bearded Girdle (heavy)
129
Name the inclusion
Br Bruise
| On facet junction
130
Name the inclusion
Br Bruise
| On facet
131
Name the inclusion
K Knot
| (darkfield)
132
Name the inclusion
K Knot
| (reflected light)
133
Name the inclusion
Patch Patch of color
134
Name the inclusion
Patch Patch of color
135
What is a bruise in the context of diamonds?
A bruise (Br) is a tiny area of impact accompanied by very small root-like feathers visible at 10x magnification.
## Footnote
A bruise is sometimes called a percussion mark.
136
How does a bruise appear when viewed through an opposing facet?
A bruise appears cottony in texture as it radiates into the diamond.
137
What is a knot in a diamond?
A knot (K) is an included diamond crystal that extends to the surface after fashioning.
138
What can be seen with magnification and proper lighting regarding a knot?
The boundary between a knot and its host diamond can be seen.
139
How is the orientation of a knot different from that of its host diamond?
A knot is oriented differently from its host diamond, which can cause problems and slow the polishing process.
140
What are the visual characteristics of a knot?
Knots sometimes look like slightly raised areas on a facet or group of facets.
141
What might be observed in reflected light concerning a knot?
You might see a knot’s outline on a facet surface and a difference in polish quality.
142
What are drag lines in relation to knots?
Drag lines happen during polishing when minute fragments of diamond are unintentionally dragged across the surface by the polishing wheel.
143
What is a patch of color on a diamond?
A patch of color (Patch) is a naturally occurring radiation stain on a polished diamond.
144
What color is a patch of color originally, and how can it change?
It’s originally green, but heat from the cutting process can turn it brown.
145
Where is a patch of color usually found?
It’s usually found on a natural surface but can also appear on the plane of a feather.
146
How are patches of color generally regarded in terms of quality?
Patches of color are usually considered blemishes.
147
Under what condition can patches of color be classified as inclusions?
If you can see that they penetrate the diamond at 10x, they’re inclusions.
148
What is a chip (Ch)?
A shallow opening on the surface located at the girdle edge, facet junction, or culet, resulting from damage after fashioning.
## Footnote
Chips typically have rounded outlines and steplike breaks, similar to the ridges on a shell.
149
What causes a chip to form?
Damage that occurs after fashioning, not accompanied by drag lines.
## Footnote
Chips are different from other surface imperfections due to their formation process.
150
Define a cavity (Cav).
An opening on the surface that occurs when part of a feather breaks away or when a crystal drops out or is forced out during polishing.
## Footnote
Cavities are typically formed during the polishing process.
151
What is an indented natural (IN)?
A portion of the original crystal surface that dips below the polished diamond’s surface, possibly featuring growth marks.
## Footnote
The original surface may have features such as trigons or parallel grooves.
152
What are the common features of chips, cavities, and indented naturals?
They can be difficult to distinguish from one another.
## Footnote
This similarity can complicate the assessment of diamond surface quality.
153
Fill in the blank: A chip typically has _______ outlines and steplike breaks.
rounded
154
True or False: A cavity is formed only when a crystal is forced out.
False
## Footnote
A cavity can also form when part of a feather breaks away.
155
Name the inclusion
Ch Chip
156
Name the inclusion
Ch Chip
157
Name the inclusion
Ch Chip
158
Name the inclusion
Cav Cavity
| Angular
159
Name the inclusion
Cav Cavity
| Reflected light
160
Name the inclusion
Cav Cavity
161
Name the inclusion
IN Intented Natural
162
Name the inclusion
IN Intented Natural
163
What is a laser drill-hole (LDH)?
A tiny tunnel produced by a laser beam extending from the surface to a dark included crystal.
164
What is internal laser drilling (ILD)?
A method that creates a surface-reaching feather or expands a pre-existing feather around a dark inclusion.
165
What is the purpose of the feather created by internal laser drilling?
To provide access for bleaching.
166
What type of channels does drilling produce in internal laser drilling?
Irregular channels that do not meet the surface.
167
What might a technician introduce into the drill-hole or feather after drilling?
Acid to dissolve or bleach the inclusion.
168
How can laser drilling affect a diamond's appearance?
It can improve the diamond's appearance and marketability.
169
What must be disclosed regarding laser drill-holes?
The presence of a laser drill-hole.
170
How does the GIA laboratory treat laser-drilled diamonds in terms of grading?
They grade laser-drilled diamonds because the drilling features are permanent.
171
Where is the presence of laser drilling treatment disclosed in a GIA report?
On the plot or in the report’s comments section.
172
Fill in the blank: The laser drill-hole extends from the surface to a _______.
[dark included crystal]
173
True or False: The channels created by internal laser drilling always meet the surface.
False
174
What is fracture filling in diamonds?
A treatment where laser drill-holes and surface-reaching feathers are filled with a molten glass substance
175
What is the purpose of fracture filling?
To make the characteristic less apparent
176
What is the flash effect?
A telltale sign indicating that a diamond is filled; it shows a flash of color that changes when tilted
177
How can you detect if a diamond is fracture-filled?
By looking for the irregularity and rocking the diamond back and forth
178
Does the GIA laboratory grade fracture-filled diamonds?
No, because the treatment is not permanent
179
What should not be confused with the flash effect?
Iridescence and orange stains caused by included iron compounds
180
Fill in the blank: The treatment of fracture filling leaves a sign called the _______.
flash effect
181
True or False: The flash effect is a permanent characteristic of diamonds.
False
182
What are the two appearance factors that might occur naturally in cleavages and fractures?
* Iridescence
* Orange stains caused by included iron compounds
183
Which assignment covers laser drilling and fracture filling in more detail?
Assignment 17
184
What are blemishes in the context of gemstones?
Blemishes are external clarity characteristics caused by wear, the cutting process, or crystal structure. They do not appear to have depth when viewed at 10x magnification.
185
What is a nick (Nck)?
A nick is a small notch on a facet junction, usually along the girdle edge or at the culet. It is smaller and shallower than a chip and has no readily apparent depth at 10x.
186
What is an abrasion (Abr)?
An abrasion is a series of minute scratches or pits along a facet junction that gives it a white or fuzzy appearance.
187
What commonly causes abrasions on gemstones?
Abrasions usually occur from careless handling and storage of jewelry, causing pieces to rub against each other. They can also happen when one diamond rubs against another in a stone paper.
188
What does the term 'paper worn' refer to?
The term 'paper worn' refers to diamonds that have rubbed against each other in a stone paper, resulting in abrasions.
189
What is a scratch (Scr) on a diamond?
A scratch is a thin, dull white line across the diamond's surface, which can be either curved or straight.
190
What is an extra facet (EF)?
A facet that’s not required by the cutting style, often located at the girdle
## Footnote
Extra facets might occur anywhere on the diamond, but are most commonly found at the girdle.
191
Why might cutters intentionally place tiny extra facets near the girdle edge?
To determine polishing directions for the star facets and upper and lower half facets
## Footnote
These extra facets might be removed or remain after fashioning is complete.
192
What is one reason a cutter might add an extra facet deliberately?
To remove or reduce an inclusion
## Footnote
This helps retain weight by avoiding the need to repolish the regular facet.
193
How can cutters unintentionally create extra facets?
By making tiny facet-adjustment errors or using an out-of-level polishing wheel
## Footnote
An extra facet could also be the remains of a window.
194
What is a window in diamond cutting?
A facet polished on the rough before cutting begins to make it easier to see inside a rough diamond
## Footnote
It is important not to confuse extra facets with additional facets.
195
How do extra facets differ from additional facets?
Extra facets are placed without regard for symmetry; additional facets are placed symmetrically
## Footnote
Additional facets are never considered blemishes.
196
What resembles an extra facet but lacks a distinct or straight facet junction?
A polish mark
## Footnote
There is very little difference in angle between a polish mark and its bordering facet.
197
What is the best way to view polishing lines?
From the opposite side of the brilliant
## Footnote
This implies that certain angles reveal imperfections more clearly.
198
What is Lizard skin (LS)?
A wavy or bumpy area on the surface of a polished diamond that occurs when the cutter polishes too close to the octahedral plane or parallel to it.
## Footnote
Lizard skin affects the aesthetic quality of the diamond.
199
What are polish lines (PL)?
Fine, tiny parallel grooves and ridges that can occur on any facet of a diamond but do not cross facet junctions.
## Footnote
They can vary from heavy to faint and are usually transparent or white.
200
How do polish lines appear on adjacent facets of a diamond?
They run in different directions on adjacent facets.
## Footnote
This directional difference helps in identifying the presence of polish lines.
201
From which side of the stone are polish lines usually easier to see?
From the opposite side of the stone.
## Footnote
This viewing method enhances visibility of surface imperfections.
202
What is Burn (Brn)?
A hazy surface area that results from excessive heat applied during polishing or occasionally from a jeweler’s torch.
## Footnote
Burn can affect the overall clarity and appearance of the diamond.
203
What is a dop burn (Dop)?
A specific type of surface burn caused by excessive heat at the location where the dop touches the diamond.
## Footnote
This can occur during the polishing process.
204
What can happen if a stone is polished too fast?
It can burn facets near the one being polished, creating a clouded or frosted look.
## Footnote
This results in a whitish film on the diamond.
205
Where might burn be visible on a diamond?
On part or all of any facet.
## Footnote
Similar to polish lines, burn is often easier to see from the opposite side of the stone.
206
Describe the blemish
Brn Burn
207
Describe the blemish
Brn Burn
208
Describe the blemish
EF Extra Facet
209
Describe the blemish
Abrasion
210
Describe the blemish
LS Lizard Skin
211
Describe the blemish
PL Polish Lines
212
Describe the blemish
PL Polish Lines
213
Describe the blemish
Scr Scratches
| Seeing from pavilion (better)
214
Describe the blemish
Scr Scratches
215
Describe inclusion
Flash effect
| This kind of diamonds are not graded
216
Describe inclusion
Flash effect
| This kind of diamonds are not graded
217
Describe inclusion
IDL Internal Laser Drilling
218
Describe inclusion
LDH Laser Drill Hole
219
Describe inclusion
Nck Nick
220
What does a rough girdle (RG) indicate?
A rough girdle indicates the irregular, pitted, or granular surface of a bruted girdle.
## Footnote
A rough girdle looks coarse, like the surface of a sugar cube.
221
What does a well-finished bruted girdle look like?
A well-finished bruted girdle looks smooth and waxy, with a frosted-glass texture.
222
What is a pit (Pit)?
A pit is a small opening that usually looks like a tiny white dot.
## Footnote
Pits usually result when pinpoint inclusions are pulled from the diamond during the polishing process.
223
What is a laser manufacturing remnant (LMR)?
A laser manufacturing remnant is a characteristic created during a laser manufacturing process, usually marking or sawing, that remains on the surface of a finished diamond.
224
When is a laser manufacturing remnant considered a blemish?
When it appears as a surface groove and shows no depth at 10x, it’s considered a blemish.
225
What happens if the laser penetrates into the diamond?
If the laser penetrates into the diamond, it can cause an internal or surface-reaching fracture, which is considered an inclusion.
226
What do the laser manufacturing remnants on a diamond appear as?
They appear across the natural's surface and along the girdle.
227
What occurs during the cutting of diamonds that may be seen on the surface?
Pits.
228
What might accompany pits during the cutting process of diamonds?
Drag lines.
229
What is a natural (N) in the context of diamonds?
A portion of the rough diamond’s original surface that remains on a fashioned stone.
230
Where are naturals typically located on a diamond?
Usually on or near the girdle, most often on the pavilion side.
231
What are growth marks that naturals might display?
Trigons and parallel grooves.
232
What is a characteristic of the surface of a natural?
Often has an uneven surface.
233
What does it indicate when a cutter leaves a natural in place?
It’s considered a sign of efficient cutting.
234
How many naturals might be present if the rough diamond was symmetrical?
There might be four naturals in opposing pairs.
235
How do naturals differ from extra facets?
Naturals show growth features and have irregular outlines, while extra facets have smooth polished surfaces and straight outlines.
236
True or False: Naturals can display cubic depressions.
True.
237
Fill in the blank: Naturals can occur at the ______, but this isn’t very common.
culet
238
What might naturals show that indicates their origin from the original crystal?
Growth marks.
239
What is surface graining (SG) in diamonds?
Surface graining consists of one or more transparent lines on the surface of a finished diamond.
## Footnote
It indicates irregularities in the diamond’s crystal structure.
240
What does surface graining indicate?
Irregularities in the diamond’s crystal structure.
## Footnote
Surface graining is related to internal graining.
241
How does polish quality relate to grain lines in diamonds?
The polish might be better on one side of a grain line than on the other.
## Footnote
This suggests variability in the finish across the surface.
242
How does surface graining differ from polish lines?
Surface graining might change direction within a facet, run in a different direction from polish lines, or cross facet junctions.
## Footnote
This can lead to a more complex appearance on the diamond surface.
243
Is surface graining removable from diamonds?
Almost impossible to remove.
## Footnote
It is part of a diamond’s distorted crystal structure.
244
Name blemish
## Footnote
Resulting from Crystal Structure
N Natural with trigons
245
Name blemish
## Footnote
Resulting from Crystal Structure
N Natural /cubic depressions/
246
Name blemish
## Footnote
Resulting from Crystal Structure
N Natural /parallel grooves/
247
Name blemish
## Footnote
Resulting from Crystal Structure
SG Surface Graining
248
Name blemish
## Footnote
Resulting from Crystal Structure
SG Surface Graining
(cubical graining)
| Reflects cubic crystal plane
249
Name blemish
## Footnote
Resulting from Crystal Structure
SG Surface Graining
| Crossing facet junction and changing direction
250
What features of a diamond can be visible at 10x magnification but do not affect the clarity grade?
Inscriptions such as text, numbers, or logos
## Footnote
Inscriptions are typically applied with a laser and located on the girdle.
251
Where are inscriptions typically located on a diamond?
On the girdle
## Footnote
Other methods of inscription application are possible.
252
How do inscriptions affect the clarity grade of a diamond?
They have no effect if confined to the surface when viewed at 10x
## Footnote
An inscription with depth visible at 10x is considered an inclusion.
253
What is considered an inclusion in a diamond?
An inscription with depth visible at 10x or totally enclosed within the diamond
## Footnote
Inclusions can affect the clarity grade.
254
What are drill-holes commonly seen on?
Briolettes or faceted diamond beads
## Footnote
Drill-holes are examples of clarity characteristics.
255
What mounting features can be added by manufacturers to secure a diamond?
Surface grooves for 'invisible' mounting
## Footnote
'Invisible' mounting refers to a setting without prongs.
256
Do mounting features affect the clarity of a diamond?
No, unless they damage the diamond
## Footnote
Damage can include characteristics like a feather or cavity.
257
Why are clarity characteristics useful?
They help identify individual diamonds and determine clarity grade and value
## Footnote
No two diamonds have the same characteristics in the same locations.
258
What will the next assignment help you do with clarity characteristics?
Determine a clarity grade
## Footnote
The assignment will involve observations of clarity characteristics.
