Chapter 11 Flashcards
What is a truly pure diamond composed of?
Carbon atoms
A pure diamond should be colorless.
What causes different colors in diamonds?
Defects in the crystal structure
What are the three elements that make up color?
- Hue
- Tone
- Saturation
What does hue represent in color?
The first impression of a color; its family identity
What is tone in the context of color?
The degree of darkness or lightness of a color
What is saturation?
The strength or intensity of a color
Are white, gray, and black considered hues?
No, they are achromatic
What does achromatic mean?
Without color
How do achromatic colors vary?
Only in darkness
What provides an ideal tone scale for achromatic colors?
The gradual progression from white through neutral grays to black
What happens to cool hues like blue as saturation drops?
They become grayish
What happens to warm hues like orange as saturation drops?
They become brownish
What occurs as saturation levels rise in colors?
Brownish and grayish components diminish
What are commonly called grays actually?
Very low saturations of various hues
Do colors with very light and very dark tones reach high saturations?
No, they do not reach saturations as high as those in medium tones
What is depth of color?
The combination of tone and saturation that impacts perception of color.
How does the depth of color affect the perception of color?
It influences how colors are perceived due to the interaction of tone and saturation.
What is the potential number of colors that can be identified by the average person?
Unlimited.
What is diamond color grading?
A demanding, painstaking process to evaluate diamond color in the D-to-Z range.
What must graders recognize in the diamond color grading process?
Very slight differences in tone and saturation.
What do graders rely on for intensely colored diamonds outside the D-to-Z range?
Well-chosen color comparison samples.
Why is understanding diamond grading procedures important?
It is essential to success in any place within the trade.
What organization established a color grading system for diamonds in the 1950s?
GIA
GIA stands for Gemological Institute of America.
What was the primary goal of GIA’s color grading system?
To clarify the color grade categories
Previous systems used vaguely defined trade terms.
What letter does the GIA color grading scale start with?
D
The letter ‘D’ is not typically associated with top quality.
How is the GIA Color Scale perceived today?
It is the most widely recognized and well-respected color grading system in the world.
What does ‘depth of color’ refer to?
The combination of tone and saturation.
What do designers rely on when selecting diamonds for elegant pieces?
GIA diamond color grading standards.
What is the universal standard in the jewelry industry for diamond color grading?
The GIA diamond color grading system.
What did GIA assemble to provide a basis for color comparison?
A set of masterstones.
What do masterstones represent in the GIA color grading system?
Known depths of color, ranging from colorless to deep yellow.
What does a masterstone graded as ‘H’ represent?
The least amount of color in that grade.
What is a split-grade masterstone?
A masterstone that represents color approximately halfway between two grades.
How are diamonds in the normal color range judged?
By their absence of color.
In what position are diamonds in the normal color range usually graded?
Table-down, or face-down position.
How are colored diamonds graded?
Through the table, in the table-up, or face-up position.
What is the first grade on the GIA Color Scale?
D (colorless)
The GIA Color Scale begins with D and continues to Z.
What does a diamond’s color grade depend on?
Tone and saturation, and absence of color
Depth of color affects the grading.
What color grades are represented by the letters on the GIA Color Scale?
D to Z
D is colorless, Z is light yellow, brown, or gray.
What does each letter on the GIA Color Scale represent?
A narrow color range
Each letter does not indicate a specific point.
How is the highest point of a color range marked on the GIA Color Scale?
By a masterstone
Each masterstone indicates the least amount of color in its range.
If a diamond has slightly less color than the H masterstone, what color grade is it?
G-color
The grading continues with F for less than G, and so on.
What happens if a diamond has less color than an E masterstone?
It is graded D
D does not require a masterstone.
How can the levels of the GIA Color Scale be categorized?
Colorless, near-colorless, faint, very light, light
These categories reflect the range of color grades.
How does viewing position affect a diamond’s color grading?
It can affect the appearance of the diamond’s color
Grading is done table-down to see subtle differences.
Fill in the blank: A diamond graded G must have less color than the _______ masterstone.
H
This indicates the grading system’s hierarchical structure.
What are the D-E-F grades in diamonds considered?
Colorless
D and E diamonds have virtually no color, and an F has a nearly undetectable amount of color.
What is the distinguishing feature of diamonds in the D-E-F grades?
Virtually no color
Differences between these grades are very slight and almost indistinguishable in diamonds smaller than 0.25 ct.
What grades are classified as near-colorless?
G-H-I-J
These diamonds look colorless face-up and nearly colorless face-down.
What do G-H-I-J grade diamonds have that isn’t noticeable to untrained eyes?
Slight traces of color
These diamonds are popular for combining fairly high color with lower prices.
What is the appearance of K-L-M grade diamonds?
Very faint color face-up and face-down
Small stones may look colorless but large ones show a slight tint.
What colors do N through R diamonds typically appear?
Very light yellow, brown, or gray
This is true even when mounted in jewelry.
How do S through Z diamonds differ in appearance?
Light yellow, brown, or gray
They show substantial color face-up or face-down, loose or mounted.
What classification is given to diamonds beyond the Z color range?
Fancy Light
This classification causes the price of the diamond to rise.
What is the grading modification for brown diamonds in the D-to-Z range?
Described with an accompanying colored diamond grade
For example, K color or darker brown diamonds are graded as Faint brown, Very Light brown, or Light brown.
How would an N-grade brown diamond be classified?
N-Very Light brown
This distinguishes it from yellow stones in that range.
How are gray diamonds graded in the colorless to near-colorless range?
They are graded with D-to-Z letter grades.
What are the word descriptions for gray diamonds beginning at grade K?
Faint Gray, Very Light Gray, Light Gray.
At what description do gray diamonds receive a colored diamond grading report?
Fancy Light.
What is the impact of color grade difference on the price of diamonds?
The difference can have a big impact on price.
Which grade shows the biggest price jump on the GIA D-to-Z scale?
The biggest jump is between the D and E grades.
How much more can a 1.00-ct. D-Flawless diamond cost compared to an E-color diamond of the same size and clarity?
Over 50 percent more.
True or False: Gray diamonds receive a colored grading report in the K-to-Z range.
False.
Fill in the blank: The grading process for gray diamonds is similar to that used for ______ diamonds.
brown
What is a key reason for the importance of accurate color grading in diamonds?
There’s still enough of a value difference farther down the color scale.
What is the minimum size requirement for diamonds submitted as masterstones?
0.25 ct.
What style must the diamonds be cut in to qualify as masterstones?
Round brilliant style
What color range is acceptable for masterstones?
Colorless to light yellow
What fluorescence levels are allowed for colors E through J?
No fluorescence
What fluorescence levels can stones in colors K through Z have?
None to Weak fluorescence
What is the minimum clarity level required for masterstones?
SI2 or better
What should be avoided in terms of inclusions in masterstones?
Eye-visible inclusions and inclusions affecting color or transparency
What proportion limits must be adhered to for masterstones?
Consistent proportions that are not noticeably shallow or deep
What type of girdles is preferred for masterstones?
Faceted girdles
What is a challenge with bruted girdles?
They can collect metal debris from tweezers
How many masterstones should a set consist of for effective color grading?
At least three masterstones
What types of diamonds are masterstones used to judge?
Yellow, brown, and gray diamonds
What should be done periodically to masterstones?
Deep cleaning and checking for damage
What should be done if a masterstone is damaged?
It should be replaced or repaired and returned for regrading
True or False: Masterstones can be treated in any way.
False
Fill in the blank: Masterstones must be unmounted and must not be _______.
diamond simulants
What is the maximum size difference allowed among masterstones in a set?
10 pts.
What historical trade term was used to describe a near-colorless diamond?
Golconda
Named after a mining area in India known for near-colorless stones.
What term was used for colorless diamonds recovered near riverbeds?
River
Reflects the typical colorless nature of diamonds found in such locations.
Which mine in South Africa produced colorless diamonds with blue fluorescence?
Jagersfontein
Diamonds from this mine were labeled ‘jagers’ due to their unique appearance.
What trade term refers to diamonds with a yellow tint from the Cape of Good Hope?
Cape
This area was known for producing mostly yellow diamonds.
Name one variation of the term ‘cape’ used to describe yellow diamonds.
- Top silver cape
- Silver cape
- Light cape
- Dark cape
Variations depend on the amount of yellow in the diamond.
True or False: The practice of using historical trade terms for diamonds is free from error.
False
Variability in diamond quality and appearance from sources leads to potential errors.
Which mine is known for producing both light yellow diamonds and some of the world’s most famous colorless diamonds?
Premier mine
Notable diamonds include the Cullinan and the Premier Rose.
What is the name of the world’s largest faceted diamond, which is a fancy-color diamond from the Premier mine?
Golden Jubilee
This diamond is yellow-brown in color.
Fill in the blank: Diamonds labeled ‘jagers’ are known for their _______ fluorescence.
blue
This characteristic is associated with diamonds from the Jagersfontein mine.
What is a potential issue with using historical trade terms for diamonds?
The color represented by the term can be misinterpreted
Definitions of trade terms are often loose, making exact descriptions difficult.
How are Golconda diamonds often defined?
Colorless with a slight bluish tinge
Definitions may vary, leading to different interpretations.
List some descriptive terms that have circulated to define diamond color.
- Blue white
- Fine white
- Commercial white
- Gem blue
The exact definitions of these terms are often unclear and misinterpreted.
Which trade term is considered the most misused?
Blue white
It has been applied to diamonds ranging from the most colorless to the yellow color range.
What warning does the Federal Trade Commission (FTC) give regarding the term ‘blue white’?
It is unfair or deceptive to use the term for any diamond showing any color other than blue or bluish under normal daylight
Misuse of this term can lead to accusations of misrepresentation.
What does the term ‘top light brown’ refer to in diamonds?
Diamonds that have slight brown color face-up
There is no specific definition for this term.
What does ‘top top light brown’ mean?
Diamonds with nearly undetectable brown color that appear almost colorless when mounted
This term is especially used for small diamonds produced by Indian manufacturers.
What is the GIA color grading system known for?
Preventing problems commonly associated with trade terms
It is used as the worldwide standard for diamond color grading.
How does the GIA color grading system improve communication about diamond color?
It provides strict guidelines for each color range, making descriptions dependable and accurate
An F-color diamond is always an F-color diamond, regardless of location.
What is a disadvantage of descriptive terms like ‘river’ or ‘canary’ in diamond grading?
They create images and associations that distract from accurate color grading
This can lead to misinterpretation of a diamond’s true color.
What can be misleading when referring to diamonds?
Using trade terms for diamonds can be misleading.
What is an example of a trade term that can be misleading?
The term ‘canary’ when referring to diamonds.
What is a limitation of the term ‘canary’ in the diamond trade?
It describes only the yellow diamond color.
Fill in the blank: Canaries exist in so many more colors than the _______ diamond color.
yellow
What is the primary requirement for color grading diamonds?
A white or neutral surface with a matte finish.
This ensures that the grading process is not influenced by surrounding colors.
What type of lighting is most widely accepted for color grading diamonds?
Balanced, daylight-equivalent fluorescent light.
This type of lighting is often provided by overhead lights on gemological microscopes.
What is a DiamondDock™?
A freestanding unit manufactured by GIA Instruments that provides a neutral background and controlled lighting conditions.
It helps create a consistent environment ideal for color grading diamonds.
What is the purpose of using masterstones graded by the GIA laboratory?
To eliminate guesswork from color grading.
Masterstones provide a reference for accurate color assessment.
Why might an appraiser need a greater variety of masterstones?
To cover more possibilities in anticipating the color of the diamonds to be graded.
This is because appraisers may deal with a wider range of diamond colors.
Fill in the blank: A set of synthetic cubic zirconia (CZ) comparison stones costs much less than a _______ masterstone set.
diamond
However, CZs do not display the same brilliance and fire as diamonds.
True or False: The colors of synthetic cubic zirconia (CZ) comparison stones remain consistent over time.
False.
CZ colors might fade over time, making them unreliable for comparison.
What materials can jewelry professionals use for creating disposable grading trays?
White business or index cards.
These can be folded to enclose diamonds in an all-white environment.
What is the advantage of using white, nonfluorescent plastic grading trays?
They provide a neutral environment for accurate color grading.
This helps block out other colors that might influence the grading process.
What is the first step after establishing the proper environment for grading diamonds?
Clean the diamond and the masterstones to be free of dust and dirt
This ensures accurate color grading.
How does the grader arrange the masterstones on the grading surface?
Table-down, left to right, lightest to darkest, about one half inch apart
This arrangement helps in systematic comparison.
What is the purpose of progressively narrowing the range during diamond grading?
To fit the unknown diamond within a single grade
This process allows for precise color classification.
Where does the grader place the diamond initially during the grading process?
To the left of the highest-graded masterstone
For example, left of the E master.
What does the grader do after placing the diamond next to the masterstones?
Moves the diamond along the row until it appears to have less color than the master to its left
This helps in identifying the closest masterstone.
What is the grading outcome if the diamond has less color than the G master but more than the F master?
The diamond’s grade is likely an F
This follows the principle of identifying the closest masterstone.
What technique does the grader use to observe the diamond’s overall color?
Rocks the grading tray with a gentle up-and-down motion
This technique reduces distracting reflections.
What happens if the unknown diamond is the same color as the closest masterstone?
Final grade cannot be determined until comparing with diamonds on right and left sides of the master
This ensures accurate classification even in color matches.
What is the grading system used for diamonds in the O-to-Z range?
A two-grade range is assigned, such as O to P, Q to R, S to T, U to V, W to X, and Y to Z.
This is due to the difficulty in distinguishing fine grade differences as color becomes more noticeable.
What must graders ensure during the grading process?
That the diamond is not switched with a masterstone.
Graders use a loupe or microscope for verification after grading.
What features do GIA masterstones have for identification?
Girdle inscriptions.
These inscriptions help separate the masterstones from unknown diamonds.
What is the purpose of the Master-Eye Effect in diamond grading?
It affects the apparent depth of color when comparing a diamond to a masterstone.
This optical illusion can influence grading decisions.
How does the grader determine if the unknown stone has a higher color grade than the masterstone?
If it appears to have the same or slightly more color on the left and less color on the right.
This indicates a higher color grade than the masterstone.
What indicates that an unknown stone is the same grade as the masterstone?
If it appears to have the same or more color on the left and the same or slightly less color on the right.
This is a critical observation during color grading.
How can graders improve their handling of the Master-Eye Effect?
Through practice and experience.
Most people encounter this effect when color grading diamonds.
What reference material is suggested for more details on color grading?
The Diamond Grading Lab Manual.
This manual provides additional insights and systematic approaches for graders.
What is the best way to determine a diamond’s color grade?
Comparing it against a set of masterstones
Masterstones provide a standard for accurate comparison.
What can be used to estimate a diamond’s color grade when masterstones are unavailable?
A simple estimation process
Estimation can be fairly accurate.
What is the first step in the diamond color grading process?
Cleaning the diamond and setting up the color grading environment
Proper lighting and background are essential.
How does the grader examine the diamond in the face-down position?
By looking perpendicular to the pavilion facets
This position provides an accurate impression of overall color.
What does the grader assess before changing the diamond’s position?
Whether the diamond is colorless, has a slight tint, or has obvious color
This judgment is crucial for accurate grading.
What effect can brilliance and fire have on color perception in diamonds?
They can mask some of a diamond’s color
This can lead to slight changes in the grader’s initial impression.
What color grade does a diamond receive if it looks colorless in both face-down and face-up positions?
D-E-F colorless range
This indicates a high-quality diamond.
If a diamond has a slight tint face-down and appears colorless face-up, what is its grade?
G-H-I-J near-colorless range
This range indicates a lower quality than D-E-F.
What grade does a diamond fall into if it shows obvious color face-down but only a slight tint face-up?
K-L-M range
This indicates more pronounced color.
What is the grade of a diamond that shows obvious color in both views?
N-to-Z range
These diamonds are considered significantly colored.
What is the final step in the diamond color grading process?
Narrowing the grade down to a single specific letter
This is based on the degree of colorlessness or faint/light coloring.
Is the estimation technique appropriate for all situations?
No
Detailed reports like appraisals require masterstones.
What factors can influence the appearance of a diamond’s color?
Factors include unusual proportions, size, and clarity characteristics.
These factors can lead to challenges in accurately grading a diamond’s color.
From which view is the color grade of a diamond mostly judged?
The color grade is mostly judged from the pavilion view.
However, the face-up appearance should also be considered.
Why is it important to look at a diamond’s face-up appearance?
It reflects how the diamond will look when set, and sometimes appears darker.
A lower grade may need to be assigned if the face-up appearance shows a color difference.
What can affect a diamond’s face-up color?
A diamond’s proportions can affect its face-up color.
Proportions that differ significantly from masterstones can complicate color grading.
How can a very shallow pavilion affect a diamond’s appearance?
It may make a diamond look lighter than a well-proportioned stone of the same color.
Conversely, a very deep pavilion can make a stone appear darker.
What is the relationship between a diamond’s size and color visibility?
Larger diamonds make it easier to see slight hints of color.
This is because thicker pieces of transparent material absorb more light.
What clarity characteristics can affect a diamond’s color appearance?
Colored inclusions and large cleavages can affect appearance.
Heavily included diamonds require comparison to the least included area of a masterstone.
How does the color of the metal affect color grading?
The color of the metal can influence the grading of mounted diamonds.
Assignment 15 discusses this aspect in more detail.
What should a grader consider if a diamond ‘just won’t color grade’?
The possibility that the diamond is coated.
This may obscure the true color of the diamond.
Fill in the blank: A very deep pavilion can make a stone appear _______.
darker
True or False: A thinner piece of material absorbs more light than a thicker piece.
False
Thicker pieces absorb more light, making their color more visible.
What factors can influence the appearance of a diamond’s color?
Factors include unusual proportions, size, and clarity characteristics.
These factors can lead to challenges in accurately grading a diamond’s color.
From which view is the color grade of a diamond mostly judged?
The color grade is mostly judged from the pavilion view.
However, the face-up appearance should also be considered.
Why is it important to look at a diamond’s face-up appearance?
It reflects how the diamond will look when set, and sometimes appears darker.
A lower grade may need to be assigned if the face-up appearance shows a color difference.
What can affect a diamond’s face-up color?
A diamond’s proportions can affect its face-up color.
Proportions that differ significantly from masterstones can complicate color grading.
How can a very shallow pavilion affect a diamond’s appearance?
It may make a diamond look lighter than a well-proportioned stone of the same color.
Conversely, a very deep pavilion can make a stone appear darker.
What is the relationship between a diamond’s size and color visibility?
Larger diamonds make it easier to see slight hints of color.
This is because thicker pieces of transparent material absorb more light.
What clarity characteristics can affect a diamond’s color appearance?
Colored inclusions and large cleavages can affect appearance.
Heavily included diamonds require comparison to the least included area of a masterstone.
How does the color of the metal affect color grading?
The color of the metal can influence the grading of mounted diamonds.
Assignment 15 discusses this aspect in more detail.
What should a grader consider if a diamond ‘just won’t color grade’?
The possibility that the diamond is coated.
This may obscure the true color of the diamond.
Fill in the blank: A very deep pavilion can make a stone appear _______.
darker
True or False: A thinner piece of material absorbs more light than a thicker piece.
False
Thicker pieces absorb more light, making their color more visible.
What is fluorescence?
The emission of visible light by a material when it is stimulated by radiation.
What fraction of natural diamonds emit some degree of fluorescence?
About one-third.
What are the identifying features of a diamond?
Fluorescence can be one of a diamond’s identifying features.
What does a grader check for when evaluating a diamond’s fluorescence?
Whether it fluoresces.
What type of report includes fluorescence descriptions for diamonds?
The GIA Laboratory Diamond Grading Report.
Is the fluorescence entry on the grading report a grade or a description?
A description.
List the terms used to describe fluorescence.
- None
- Faint
- Medium
- Strong
- Very Strong
What additional information is noted if fluorescence is Medium or stronger?
Its color.
What colors might fluorescence be described as?
- Medium yellow
- Strong blue
How does a grader determine the fluorescence of a diamond?
By placing the diamond a short distance away from a source of longwave UV radiation.
What classification is given if there’s no obvious fluorescence?
None.
What is required for a grader to accurately describe fluorescence?
Experience seeing many diamonds with varying degrees of fluorescence.
Can some diamonds change color temporarily when exposed to UV radiation?
Yes, it’s rare but possible.
Why is it important to evaluate color before determining fluorescence?
Because some diamonds may change color temporarily when exposed to UV radiation.
