Chapter 15 Flashcards
(126 cards)
1
Q
What do retail jewelers routinely take in for repair?
A
Mounted diamonds
Retail jewelers handle mounted diamonds for various repair services.
2
Q
Who do retail jewelers increasingly work with to improve diamonds?
A
Cutters
Jewelers collaborate with cutters for repolishing and recutting stones.
3
Q
What might dealers arrange for poorly cut diamonds?
A
Recutting
Dealers may arrange for the recutting of diamonds that are not selling well.
4
Q
What is a benefit of recutting diamonds?
A
Better proportions and improved light return
Recutting can enhance the marketability of diamonds.
5
Q
True or False: The loss of weight in diamonds is sometimes worth the improvement in marketability.
A
True
Retail jewelers may accept some weight loss for better quality diamonds.
6
Q
Where are most diamonds bought or sold at the retail level?
A
Most diamonds are bought or sold mounted in jewelry
Jewelers and consumers rarely deal in loose stones.
7
Q
What challenges does mounting a diamond create?
A
Mounting makes it difficult to assess a diamond
It can hide imperfections, affect apparent color, and make weighing and measuring challenging.
8
Q
What is a significant limitation of grading mounted diamonds?
A
Grades for mounted diamonds are less accurate and consistent than for loose stones
This is due to the reliance on estimates and value judgments.
9
Q
What type of diamond grading reports does the GIA laboratory issue?
A
The GIA laboratory only issues diamond grading reports for loose stones
This ensures more accurate assessments.
10
Q
Fill in the blank: It is impossible to accurately weigh a _______ diamond.
A
mounted
11
Q
True or False: Mounted diamonds can hide a diamond’s imperfections.
A
True
12
Q
What part does estimation play in the grading of mounted diamonds?
A
Estimation plays an important part in the grading of mounted diamonds
This is due to difficulties in assessment.
13
Q
What techniques are used for grading clarity in diamonds?
A
The same techniques are used for loose and mounted diamonds, with added considerations for mountings
Mountings can limit viewing angles and interfere with lighting
14
Q
How can a fiber-optic lighting system assist in grading diamonds?
A
It allows adjustable brightness and focus, directing light where needed
This helps in finding inclusions and evaluating clarity
15
Q
What is a common issue when grading clarity for mounted diamonds?
A
Prongs can hide blemishes and inclusions
Inspecting the area around prongs is necessary to find hidden inclusions
16
Q
What should you do with higher-clarity diamonds for accurate grading?
A
Remove the diamond from the mounting
This is important as the difference between IF and VVS can significantly affect value
17
Q
How do appraisers typically report clarity grades for mounted diamonds?
A
They state a single clarity grade for large diamonds and a range of two grades for small ones
Mounted diamonds are indicated as such in appraisals
18
Q
What effect can a mounting have on color grading?
A
It can inhibit accurate grading by interfering with clear pavilion views
The metal of the mounting may also influence the diamond’s apparent color
19
Q
What magnification is recommended for evaluating the color of mounted diamonds?
A
10x magnification
This is essential for comparing the diamond to masterstones
20
Q
How are color grades assigned to small mounted stones?
A
They typically receive a range of two possible color grades
This compensates for the difficulty of grading smaller stones
21
Q
What is the process for evaluating a mounted diamond’s measurements?
A
It is similar to loose stones, but may require estimation if the girdle edge is covered
Estimations may be needed for dimensions when the mounting obstructs views
22
Q
How can you assess the girdle’s thickness and condition in a bezel setting?
A
Check its reflection in the pavilion
Look for uniform gray streaks for bruted girdles or speckled reflections for dirty girdles
23
Q
What should you do to judge the girdle’s thickness in a prong-set stone?
A
Observe visible areas and assess hidden areas by tilting the stone
This helps in evaluating the girdle’s condition accurately
24
Q
How is girdle thickness percentage calculated?
A
By subtracting crown height percentage and pavilion depth percentage from total depth percentage
Estimations can be used when direct measurements are not possible
25
Fill in the blank: A mounting can ______ accurate color grading.
inhibit
## Footnote
This is due to interference with a clear pavilion view
26
What method can be used for observing diamonds in a solitaire setting?
Hold the mounting so the diamond is in the table-down position while moving it along the row of masters.
## Footnote
This method allows for direct comparison with loose stones.
27
What is the second method for observing diamonds?
Hold the masterstone in tweezers with its table close to the table of the mounted diamond to compare their crown areas.
## Footnote
This method requires careful observation of the corresponding crown areas.
28
What should you do if the crown is not visible in the profile view?
Hold the diamond and the masterstone side by side for a face-up color comparison.
## Footnote
This allows for a direct visual comparison of color when the crown cannot be observed.
29
What is the color grading assignment for large stones?
A single color grade
## Footnote
Large stones are evaluated with a straightforward grading system.
30
What happens to the color grading task as the size of the stone decreases?
It becomes more difficult
## Footnote
Smaller stones can appear similar in color despite differing grades.
31
What is the common issue when examining small mounted stones side by side?
Colors can look similar despite differing by two or three color grades
## Footnote
This similarity complicates accurate grading.
32
What color grading range do appraisers generally give to small mounted stones under 0.20 ct?
A range of two possible color grades
## Footnote
This approach helps account for the challenges in grading smaller stones.
33
What should be noted when grading stones under mounting limitations?
The stone was graded under the limitations imposed by a mounting
## Footnote
This acknowledgment is important for transparency in grading.
34
How do you judge the pavilion depths and angles of rounds?
The same for loose and mounted stones.
35
What method is used to estimate pavilion depth percentage from crown height percentage?
Multiply the crown height percentage by the visual estimation of the relationship between the pavilion depth and the crown height.
36
If a diamond’s crown height percentage is 14.4% and its pavilion is three times as deep as its crown, what is the pavilion depth percentage?
43.2% rounded to 43%.
37
How do you estimate a round diamond’s pavilion depth if you know its total depth percentage, crown height percentage, and girdle thickness percentage?
Add the crown height percentage to the girdle thickness percentage and subtract that total from the total depth percentage.
38
What is the typical pavilion depth ratio for well-made diamonds?
Between 2.5 and 4.5 times the depths of their crowns.
39
How can you determine total depth percentage of a diamond?
Get the measuring device to contact the diamond’s culet and convert the millimeter figure to a percentage.
40
To calculate pavilion depth percentage for fancy shapes, what should you divide and multiply?
Divide the diamond’s depth by its width, multiply by 100, and round to the nearest tenth of a percent.
41
Fill in the blank: The formula for estimating pavilion depth percentage involves subtracting the sum of crown height percentage and ______ from total depth percentage.
girdle thickness percentage.
42
True or False: The pavilion depth can be visually judged on fancy cuts if the mounting allows you to see the stone’s profile.
True.
43
What should you do when you can't see or measure the pavilion?
Make the best estimation you can
## Footnote
This emphasizes the importance of estimation skills in gemology.
44
How should you judge culet size in a mounted diamond?
By looking through the table
## Footnote
This method is similar to judging culet size for loose diamonds.
45
What aspects should you evaluate in a mounted diamond?
Polish and symmetry
## Footnote
These should be judged as you would on a loose stone.
46
What can be used to see areas hidden by the mounting?
Reflections
## Footnote
Reflections can help identify hidden imperfections.
47
What tool can be used to estimate the cut grade of a mounted round brilliant diamond?
GIA Facetware® Cut Estimator
## Footnote
This is an online tool specifically designed for cut grade estimation.
48
What are good alternatives to the online cut estimator when Internet access is unavailable?
Visual estimation techniques explained in Assignments 12 and 13
## Footnote
These techniques provide practical skills for estimating cut grades.
49
What do diamond professionals use to estimate the weights of mounted round and fancy-cut diamonds?
Mathematical formulas
## Footnote
The formulas assume fairly standard, modern proportions and basically symmetrical designs.
50
What should be considered when using weight estimation formulas for diamonds?
Proportion variations
## Footnote
No single formula can apply to every variation in shape and proportion.
51
What is the effect of extreme variations in diamond shape and proportion on weight estimation?
Affect accuracy
## Footnote
Extreme variations can significantly impact the weight estimation results.
52
What is crucial to use for accurate weight estimation?
The correct weight estimation formula
## Footnote
Watch for proportion variations that require adjustments.
53
What common mistake should be avoided when estimating weight?
Placement of decimal points
## Footnote
It's easy to make mistakes in writing measurements or calculations.
54
What should you do after calculating a weight estimate for a diamond?
Take a last look at the stone to see if the estimate is reasonable
## Footnote
This step helps ensure accuracy in the estimation process.
55
What types of gems do the weight estimation formulas specifically apply to?
Diamonds
## Footnote
These formulas do not work for other types of gems.
56
What is the key to accurate weight estimation in diamond grading?
Experience
## Footnote
Practice with loose stones helps refine estimation skills.
57
What is the typical accuracy range skilled graders can achieve in weight estimation?
Within 10 percent
## Footnote
For example, a stone estimated at 1.00 ct. might weigh between 0.90 and 1.10 cts.
58
What should be included in appraisals or business forms regarding weight estimation?
A qualifying statement
## Footnote
Such as 'weight estimated by formula from measurements.'
59
What effect does a thick girdle have on estimated diamond weight?
Adds weight at the widest part
## Footnote
Girdle thickness has the greatest effect on estimated weight.
60
What chart should be used to adjust for thicker girdles in weight estimation?
Weight Correction Factors for Thicker Girdles chart
## Footnote
This chart helps account for the additional weight contributed by a thick girdle.
61
What is the confusion to avoid when estimating total depth percentage?
Confusing the Weight Correction Factors chart with the Estimated Girdle Thickness Percentage chart
## Footnote
Each chart serves a different purpose in weight estimation.
62
What is the range of weight corrections required for girdle thickness in diamonds?
1 to 12 percent
## Footnote
Weight corrections are necessary for all shapes of diamonds.
63
What types of variations in girdle outline require weight corrections for fancy cuts?
* High shoulders on pear shapes and ovals
* Bulged wings on pears, hearts, and marquises
* Pavilion bulge on emerald cuts
## Footnote
These variations impact the weight estimation of fancy-cut diamonds.
64
How do you determine the total weight correction when using adjustments for girdle thickness and outline?
Add the corrections for girdle thickness and girdle outline
## Footnote
For example, if you have a 3 percent adjustment for thickness and a 5 percent for outline, the total is 8 percent.
65
If there is a 3 percent adjustment for girdle thickness and a 5 percent correction for girdle outline, what is the total weight correction?
8 percent
## Footnote
This is calculated by adding the two percentages together.
66
What percentage do you use in the weight estimation formula when the total weight correction is 8 percent?
108 percent
## Footnote
This is derived by adding 100 percent to the total weight correction.
67
What should you do when there’s no correction for girdle thickness or outline shape?
Drop the weight correction from the formula
## Footnote
This means you would use 100 percent in the weight estimation.
68
What information do you need to estimate the weight of a round brilliant diamond?
* Average diameter in millimeters
* Depth in millimeters
* Overall girdle thickness
## Footnote
These measurements are essential for accurate weight estimation.
69
How do you find the average diameter of a prong-set stone?
Measure the girdle diameter in multiple places between the prongs, record the smallest and largest measurements, add them, and divide by two. Round to the nearest hundredth (0.01) of a millimeter.
70
What is the method for estimating the diameter of a bezel-set stone?
Estimate the diameter across all four pairs of bezel facets.
71
What should you do if you cannot measure the depth directly?
You have to estimate the depth.
72
What dimensions are required to estimate the weights of fancy cuts?
Length and width.
73
In fancy cuts, how is length defined?
Length is the longest dimension.
74
In fancy cuts, how is width defined?
Width is the longest of the dimensions that are perpendicular to the length.
75
For a triangle with equal sides, how can width be determined?
Any side can be the width.
76
If a triangle’s sides are not equal, how do you choose the width?
Use the noticeably longer or shorter side as the width.
77
How is the length of a triangle defined?
Length is the distance from the center of the side used as width to the opposite point.
78
Can a triangle's length be shorter than its width?
Yes, a triangle’s length can be shorter than its width.
79
What does the length of a heart shape measure?
The distance from the point to an imaginary line across the tops of the lobes.
80
What is the vulnerability of points on marquises, pears, hearts, and triangles?
They are vulnerable to chipping.
81
What feature is often used to protect vulnerable points on certain cuts?
V-corners or prongs covering these areas.
82
What should you do if metal covers the girdle along the length or width?
Estimate where the edge is and measure from there.
83
What is the adjustment factor for weight estimation for round brilliants?
0.0061.
84
What is the adjustment factor derived from?
Trial and error while working with thousands of diamonds of certain dimensions and known weights.
85
Are there adjustment factors for shapes other than round brilliants?
Yes, there are similar adjustment factors for other shapes.
86
What is included as part of the weight estimation formulas?
Adjustment factors for different shapes.
87
What is the adjustment factor for elongated cuts like emerald cuts and radiant cuts?
There’s no universal adjustment factor.
88
What additional calculation is required for weight estimation of elongated cuts?
Length-to-width ratio.
89
How do you calculate length-to-width ratio?
Divide length by width and round to the nearest hundredth (0.01) of a millimeter.
90
Which cuts require an additional calculation for weight estimation?
* Emerald cuts
* Radiant cuts
* Marquises
* Pears
91
Round brilliant estimation formula
AVGxDepthx0,0061x weigh correction
92
Oval brilliant estimation formula
AVGxAVGxDepthx0,0062xWeight correction
| AGD= (L+W)/2
93
Heart brilliant estimation formula
LxWx0.0058xWeightCorrection
94
Triangular brilliant estimation formula
LxWxDepthx0.0057xWeightCorrection
95
Square or rectangular brilliant estimation formula
LxWxDepthx0.0083xWeight Correction
96
What is the hardest substance found in nature?
Diamond
97
Can diamonds be damaged despite being the hardest substance?
Yes
98
What can cause damage to a diamond?
Abrasion of facet junctions, knocking off corners, chipping of girdles
99
Which shapes of diamonds are more prone to damage?
Shapes with points
100
What is the purpose of repolishing a diamond?
To restore or improve the appearance of a diamond
101
What does repolishing usually involve?
Refinishing a diamond to correct minor faults in its clarity or finish
102
What might a cutter do during the repolishing process?
Eliminate nicks, abrasions, or small chips
103
What are some methods a cutter might use to replace nicks or chips?
Adding extra facets
104
What are diamonds judged to be potentials or improvables by?
A diamond grading lab like the GIA laboratory
105
What does the grading lab specify regarding the diamond's clarity grade?
How it might be improved by repolishing
106
Fill in the blank: Repolishing and _______ have the same purpose.
Recutting
107
What is the highest clarity grade a potential can reach?
Internally Flawless (IF)
## Footnote
Clarity grades indicate the presence of inclusions or blemishes in a diamond.
108
To which grades can improvables typically be raised with minor repolishing?
VVS1 or VVS2
## Footnote
VVS stands for Very Very Slightly Included, indicating minor inclusions.
109
What three factors determine the effect of a clarity-improving repolish on a diamond’s value?
* The stone’s color
* Its old and new clarity grades
* The finished weight
## Footnote
These factors influence how much the diamond's value can increase after repolishing.
110
Which color grades are most affected by improvements in clarity?
D-to-G color grades
## Footnote
Diamonds in this range tend to be more valuable and are typically clearer.
111
What operation can improve a diamond's color by polishing?
Polishing or faceting a previously bruted girdle
## Footnote
This process removes foreign matter and can lighten the diamond’s color.
112
What does full recutting of a diamond involve?
Refashioning a polished diamond to improve clarity, proportions, or color
## Footnote
It may also modernize an old-style cut.
113
Is complete recutting always necessary for repairing damage to a diamond?
No
## Footnote
Sometimes only specific parts like the crown or pavilion need repair.
114
What are potential outcomes for a damaged round diamond during recutting?
* It might be recut as a round
* It might be recut as a different fancy cut
## Footnote
This depends on the extent of the damage and desired outcome.
115
What is the primary consideration in diamond recutting?
The value of the resulting finished diamond
## Footnote
This value is determined by a combination of weight and beauty.
116
What is the common compromise when recutting a diamond?
Weight versus beauty
## Footnote
Owners typically prioritize weight but balance it with aesthetic improvements.
117
What is essential to know before deciding to recut a diamond?
What the recut diamond will weigh
## Footnote
Weight estimates can be uncertain until recutting is complete.
118
What factors should be considered besides weight when recutting a diamond?
* Current appearance
* Expected future appearance
* Value of the diamond
* Cost of recutting
## Footnote
These factors help in making an informed decision about recutting.
119
What determines a diamond’s brightness, fire, and scintillation?
A diamond’s proportions
## Footnote
The proportions of a diamond affect its visual appeal and performance.
120
Why are most stones recut?
To improve their brightness and balance between brightness and fire
## Footnote
Recutting can enhance the attractiveness of a stone.
121
What should be considered before recutting a diamond?
Minimum loss of weight and apparent size
## Footnote
Weight loss can affect the overall value of the diamond.
122
What factors influence the degree of improvement and recut weight?
The specific problem the recut is intended to solve
## Footnote
Each diamond presents unique challenges and opportunities.
123
What role does the cutter’s opinion play in the recutting process?
It is valuable and should be carefully considered
## Footnote
Cutters may advise against recutting if it risks damaging the stone.
124
Why might diamonds be recut to improve clarity?
To eliminate inclusions
## Footnote
However, this can be expensive due to weight loss and labor costs.
125
What could be a reason for a previous cutter to leave an inclusion in a diamond?
It was too costly to remove it
## Footnote
Removing inclusions often involves significant expense.
126
What are two less expensive alternatives to recutting for improving clarity?
Laser drilling and bleaching
## Footnote
These methods can sometimes provide clarity improvements without the costs of recutting.
