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GIA Diamonds and Diamond Grading Final Exam
#2 With Complete Solution
London Diamond Syndicate - ANSWER What group was critical to De Beers's early sales strategy?
Color - ANSWER How are gem-quality rough diamonds sorted?
Baby Boomers - ANSWER What generation was first to connect with diamonds as a representation of lifetime commitment?
India - ANSWER Where did the diamond industry first start?
Single-channel marketing - ANSWER What describes the concept of centrally controlled supply, purchase, promotion, and sales of rough diamonds?
Lower mantle - ANSWER What mantle layer is most dense?
Will turn into graphite - ANSWER What happens to diamond if lamproite stalls in the continental crust?
When a continental and oceanic plate collide - ANSWER When does subduction occur?
High heat and high pressure - ANSWER How are metamorphic rocks formed?
CLIPPIR diamonds, blue diamonds, Brazil's Junia diamond - ANSWER What is an example of a superdeep diamond?
A good sign that a pipe is nearby - ANSWER What might black spinel in a mineral sample indicate?
Robotic/automated crawlers - ANSWER What equipment might offshore
deep-sea diamond mining use?
Primary deposits - ANSWER What deposit type produces most diamonds mined today?
Character sampling - ANSWER What type of sampling gives an initial idea of diamond quality for a deposit?
Brazil - ANSWER Where are rocks and geological structures similar to Africa found due to ancient connections?
Crystal structure - ANSWER What is another term for crystal lattice?
Type Ia - ANSWER What type are most natural diamonds?
Cleavage - ANSWER What is a smooth, flat break in a crystal parallel to a cleavage plane?
Macle - ANSWER What is a flat, triangular, twinned diamond crystal?
Intrinsic defect and extrinsic defects - ANSWER What types of point defects are found in diamonds?
Color center - ANSWER What influences light absorption, resulting in bodycolor?
Hydrogen-related defects - ANSWER What trace element can cause a violet color in diamonds?
Lower - ANSWER How does the energy emitted by a gem compare to the energy it absorbs?
White light - ANSWER What type of light combines all the colors in the visible spectrum?
Old European cut - ANSWER What was the prototype of the modern round brilliant cut?
Holds/secures a diamond in place - ANSWER What does a dop do?
High pressure, high temperature - ANSWER What does HPHT stand for?
Cuboctahedrons - ANSWER What rough form does NOT appear in natural diamonds
Type 1b - ANSWER What diamond type can be created by the HPHT method?
CVD lab-grown diamonds - ANSWER What diamonds have strain pattern and intensity similar to natural diamonds?
At every step - ANSWER When should the origin of a lab-grown diamond be disclosed?
Internal laser drilling - ANSWER What diamond clarity treatment expands inclusions?
Annealing - ANSWER What diamond color treatment further modifies color by allowing vacancies and trace elements to diffuse post-irradiation?
Graphitization - ANSWER What describes the formation of graphite around a diamond's mineral inclusions and feathers?
Fracture filling - ANSWER What diamond clarity treatment relies on similar refractive index (RI) values?
HPHT treatment can move and rearrange defects in a diamonds crystal lattice
- ANSWER How can HPHT treatment alter a diamond's color?
Transparent - ANSWER What feature can a colorless diamond and a simulant have in common?
Fire - ANSWER What can help rapidly identify a strontium titanate doublet?
Less expensive - ANSWER What is a benefit of simulants?
Lower - ANSWER What is a diamond's heft in relation to most simulants?
Pick price - ANSWER What parcel price comes at a premium?
Per-carat price - ANSWER How do dealers quote diamond prices?
Inclusions - ANSWER What is the term for flaws or imperfections in a diamond?
Loupe/microscope - ANSWER What can help determine a clarity characteristics location?
Blemishes - ANSWER What clarity characteristic is found only on the surface of a gemstone?
Cavity - ANSWER What clarity characteristic results when a crystal is expelled?
Directly under the table - ANSWER Where are inclusions most visible?
Cloud or pinpoint - ANSWER What kind of clarity characteristic is not seen at 10x mag.?
Relief - ANSWER What describes the contrast btwn an inclusion and the diamond?
Noticeable inclusions that are very easy to see at 10x mag. - ANSWER What best describes the clarity characteristics in SI1 and SI2 stones?
Plotted on both the crown and pavilion diagrams - ANSWER Where is a feather that reaches both the crown and pavilion plotted?
Degree of darkness or lightness - ANSWER What is a term that describes tone?
Gray - ANSWER What color becomes more prominent as cool hues become less saturated?
Light - ANSWER What term falls on the GIA D-to-Z color scale?
Diamonds - ANSWER What material are masterstones?
Face-up - ANSWER What position are colored diamonds color graded in?
Misshapen facets - ANSWER What might be found in a diamond with misalignment (Aln)?
Make it look foggy - ANSWER How do shallow pavilion angles affect appearance?
Mixed cut - ANSWER What style describes a diamond that has both brilliant-cut and step-cut facets?
Shoulders - ANSWER What is the area between the head and belly of an oval?
Width of stone (instead of average girdle diameter) - ANSWER What is used for total depth percentage calculation in fancy shapes?
Too many variations - ANSWER Why is there no single cut grading standard for fancy cuts?
French tip - ANSWER What style helps avoid point breakage in fancy cuts?
2:1 - ANSWER What is the length-to-width ratio for a fancy cut 4.00mm long and 2.00mm wide?
Mathematical formulas - ANSWER How do diamond professionals estimate the weight of mounted diamonds?
Single grade - ANSWER What do appraisers assign to larger mounted diamonds when color grading?
Improvable - ANSWER What term describes a diamond whose clarity can become VVS after repolishing?
Remove color zoning (rarely used) OR increase color - ANSWER What is a good case for recutting?
Bourse - ANSWER A diamond buying and selling club (they have them in trading centers)
Peridotite - ANSWER A type of rock that diamonds form in
- igneous rock (formed from a molten state)
- most diamond form in this rock
- has consistent release of carbon
- block caving is the alternative to this
Pipe, alluvial, and marine deposits - ANSWER Most of the diamonds that come from Africa are recovered from _______ deposits
Primary sources - ANSWER Most of the diamonds that come from Russia are recovered from ______ sources.
3.52 - ANSWER What is the specific gravity of a gem-quality diamond?
Marine deposits - ANSWER Diamonds are more concentrated in which type of deposit?
Look for the oldest parts of the earths crust - ANSWER The first step in exploring for diamonds is to _____
The world's supply of diamond rough has increased (more diamonds are available to people) - ANSWER The diamond industry has changed dramatically in recent years because _____
India - ANSWER The Argyle mind in Australia contributed to the rise of the cutting industry in _____
Dodecahedral - ANSWER What is the softest crystal direction in diamond?
Isometric or cubic crystal structure - ANSWER What crystal structure does diamond belong to?
Cubic (runs horizontal), octahedral (on face), dodecahedral (runs vertical) - ANSWER What are diamond's 3 internal crystal planes?
Octahedral planes - ANSWER The crystal planes most suitable for cleaving a diamond are the _______ planes?
Isometric - ANSWER Another name for the cubic system
Blocker - ANSWER Polishes the crown and pavilion mains
Brillianteering - ANSWER Polishing of the star and upper and lower half facets
Kites - ANSWER Bezel facets are the ones shaped like ____
Pit - ANSWER Blemish; A small opening that looks like a tiny white dot at 10x
Know - ANSWER An included diamond crustal that extends to the surface after fashioning
Needle - ANSWER A long, thin crystal that looks like a tiny rod at 10x
Pinpoint - ANSWER A very small included crystal that looks like a tiny dot at 10x
Cloud - ANSWER Many tightly grouped pinpoints
Twinning wisp - ANSWER A series of pinpoints, clouds, or crystals that form in the diamond's growth plane
The five clarity factors - ANSWER Size, number, location, relief, nature
Requirements for a Flawless diamond - ANSWER No inclusions or blemishes under 10x can have these features:
- extra facets not visible face-up
- naturals confined to the girdle as long as they don't thicken the girdle or distort its outline
- internal graining that's not reflective, white, colored, and doesn't affect transparency
- inscriptions that don't penetrate the surface
Requirements for a VVS1 and VVS2 - ANSWER Contain minute inclusions that are difficult to see under 10x
VVS1:
- inclusions are extremely difficult to see face-up; pinpoint or two, possible internal graining not seen face-up
VVS2:
- inclusions are very difficult to see; surface-reaching inclusions possible
Requirements for a VS1 and VS2 - ANSWER Contain minor inclusions that range from difficult (VS1) or somewhat difficult (VS2) to see at 10x
- all inclusions are possible, grade depends on overall visibility
Requirements for a SI1 and SI2 - ANSWER Noticeable inclusions that are easy (SI1) or very easy (SI2) to see at 10x
- all inclusions are possible, grade depends on visibility
pure vivid)
Hue - ANSWER The basic color of an object
Craftsmanship - ANSWER The care that goes into the fashioning of a polished diamond, as confirmed by its finish
Design - ANSWER A diamond's physical shape, including its proportions and durability, determined by decisions made during the fashioning process
Finish - ANSWER The quality of the polish and precision of the cut of a fashioned gemstone
The bowing method - ANSWER Uses the star facets to estimate table %
- star facets should be 1/2 of the way from table edge to girdle
- if they go 1/3 of the way...CAUSES IT TO BOW IN (subtract 6% from estimate)
- if they go 2/3 of the way...CAUSES IT TO BOW OUT (add 6% to the estimate)
Use the bowing method; If the lines are straight, the table % is about... - ANSWER 60%
Use the bowing method; If the lines bow in noticeably, the table % is about...
Use the bowing method; If the lines bow in slightly, the table % is about... - ANSWER 58%
Use the bowing method; If the lines bow out slightly, the table % is about... - ANSWER 63%
Use the bowing method; If the lines bow out noticeably, the table % is about... - ANSWER 67%
The flash method - ANSWER Used to estimate table %
- simplest and quickest method but need experience looking at lots of different table sizes
- Small flash = table % less than 60%
- Medium flash = table % is 60-64%
- Large flash = table is 65% or more
The ratio method - ANSWER Used to estimate table %
