Download GIA Diamonds and Diamond Grading Final Exam #2 with 194 correct solutions Graded A+. GIA D and more Exams Mechanical Engineering in PDF only on Docsity!
Final Exam #2 with 194 correct solutions
Graded A+.
GIA Diamonds and Diamond Grading
Final Exam #2 with 194 correct solutions
Graded A+.
What group was critical to De Beers's early sales strategy? - ANSWER London Diamond Syndicate
How are gem-quality rough diamonds sorted? - ANSWER Color
What generation was first to connect with diamonds as a representation of lifetime commitment? - ANSWER Baby Boomers
Where did the diamond industry first start? - ANSWER India
What describes the concept of centrally controlled supply, purchase, promotion, and sales of rough diamonds? - ANSWER Single-channel marketing
What mantle layer is most dense? - ANSWER Lower mantle
What happens to diamond if lamproite stalls in the continental crust? - ANSWER Will turn into graphite
When does subduction occur? - ANSWER When a continental and oceanic plate collide
How are metamorphic rocks formed? - ANSWER High heat and high pressure
What is an example of a superdeep diamond? - ANSWER CLIPPIR diamonds, blue diamonds, Brazil's Junia diamond
Final Exam #2 with 194 correct solutions
Graded A+.
What might black spinel in a mineral sample indicate? - ANSWER A good sign that a pipe is nearby
What equipment might offshore deep-sea diamond mining use? - ANSWER Robotic/automated crawlers
What deposit type produces most diamonds mined today? - ANSWER Primary deposits
What type of sampling gives an initial idea of diamond quality for a deposit? - ANSWER Character sampling
Where are rocks and geological structures similar to Africa found due to ancient connections? - ANSWER Brazil
What is another term for crystal lattice? - ANSWER Crystal structure
What type are most natural diamonds? - ANSWER Type Ia
What is a smooth, flat break in a crystal parallel to a cleavage plane? - ANSWER Cleavage
What is a flat, triangular, twinned diamond crystal? - ANSWER Macle
What types of point defects are found in diamonds? - ANSWER Intrinsic defect and extrinsic defects
What influences light absorption, resulting in bodycolor? - ANSWER Color center
What trace element can cause a violet color in diamonds? - ANSWER Hydrogen-related defects
Final Exam #2 with 194 correct solutions
Graded A+.
What does HPHT stand for? - ANSWER High pressure, high temperature
What rough form does NOT appear in natural diamonds - ANSWER Cuboctahedrons
What diamond type can be created by the HPHT method? - ANSWER Type 1b
What diamonds have strain pattern and intensity similar to natural diamonds? - ANSWER CVD lab-grown diamonds
When should the origin of a lab-grown diamond be disclosed? - ANSWER At every step
What diamond clarity treatment expands inclusions? - ANSWER Internal laser drilling
What diamond color treatment further modifies color by allowing vacancies and trace elements to diffuse post-irradiation? - ANSWER Annealing
What describes the formation of graphite around a diamond's mineral inclusions and feathers? - ANSWER Graphitization
What diamond clarity treatment relies on similar refractive index (RI) values? - ANSWER Fracture filling
How can HPHT treatment alter a diamond's color? - ANSWER HPHT treatment can move and rearrange defects in a diamonds crystal lattice
What feature can a colorless diamond and a simulant have in common? - ANSWER Transparent
Final Exam #2 with 194 correct solutions
Graded A+.
What can help rapidly identify a strontium titanate doublet? - ANSWER Fire
What is a benefit of simulants? - ANSWER Less expensive
What is a diamond's heft in relation to most simulants? - ANSWER Lower
What does an electronic scale require immediately after is it leveled for accurate measurement? - ANSWER Calibration
What term describes an expert diamond dealer or manufacturer? - ANSWER Diamantaire
What is a sieve set? - ANSWER Set of circular plates, each punched with precisely sized holes, used for sorting small, round gems by size
What does cooling a diamond do to spectral absorption peaks? - ANSWER Sharpens spectral absorption peaks and allows gemologists to identify the optical defects in the diamond
What can UV-Vis-NIR spectroscopy help identify? - ANSWER A diamond's absorption of visible light, portions or UV light and infrared regions close to the visible range
What is an agreement that involves multiple payments over time? - ANSWER Terms of payment
What is the per-carat price of a 2ct diamond selling for $40,000? - ANSWER $20,
What parcel price comes at a premium? - ANSWER Pick price
How do dealers quote diamond prices? - ANSWER Per-carat price
Final Exam #2 with 194 correct solutions
Graded A+.
What material are masterstones? - ANSWER Diamonds
What position are colored diamonds color graded in? - ANSWER Face-up
Where is the focus when color grading a heavily included diamond? - ANSWER The least included area
How do you measure a diamond's depth? - ANSWER Millimeter gauge OR as a percentage of its average diameter
How many star facet lengths on a round brilliant diamond are estimated before averaging? - ANSWER 8
What weight retention method can change the balance of the diamond's face-up pattern? - ANSWER Painting
What facet forms the pavilion angle when it meets the girdle plane? - ANSWER Pavilion
What pavilion depth percentage might reflect the girdle face-up through the table? - ANSWER 37%
Why do diamonds with thick girdles offer less value? - ANSWER Paying for more weight than you see
What might be found in a diamond with misalignment (Aln)? - ANSWER Misshapen facets
How do shallow pavilion angles affect appearance? - ANSWER Make it look foggy
What style describes a diamond that has both brilliant-cut and step-cut facets? - ANSWER Mixed cut
What is the area between the head and belly of an oval? - ANSWER Shoulders
Final Exam #2 with 194 correct solutions
Graded A+.
What is used for total depth percentage calculation in fancy shapes? - ANSWER Width of stone (instead of average girdle diameter)
Why is there no single cut grading standard for fancy cuts? - ANSWER Too many variations
What style helps avoid point breakage in fancy cuts? - ANSWER French tip
What is the length-to-width ratio for a fancy cut 4.00mm long and 2.00mm wide? - ANSWER 2:
How do diamond professionals estimate the weight of mounted diamonds? - ANSWER Mathematical formulas
What do appraisers assign to larger mounted diamonds when color grading? - ANSWER Single grade
What term describes a diamond whose clarity can become VVS after repolishing? - ANSWER Improvable
What is a good case for recutting? - ANSWER Remove color zoning (rarely used) OR increase color
A diamond buying and selling club (they have them in trading centers) - ANSWER Bourse
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 - ANSWER Peridotite
A type of rock that diamonds for in
Final Exam #2 with 194 correct solutions
Graded A+.
Diamonds are more concentrated in which type of deposit? - ANSWER Marine deposits
The first step in exploring for diamonds is to _____ - ANSWER Look for the oldest parts of the earths crust
The diamond industry has changed dramatically in recent years because _____ - ANSWER The world's supply of diamond rough has increased (more diamonds are available to people)
The Argyle mind in Australia contributed to the rise of the cutting industry in _____ - ANSWER India
What is the softest crystal direction in diamond? - ANSWER Dodecahedral
What crystal structure does diamond belong to? - ANSWER Isometric or cubic crystal structure
What are diamond's 3 internal crystal planes? - ANSWER Cubic (runs horizontal), octahedral (on face), dodecahedral (runs vertical)
The crystal planes most suitable for cleaving a diamond are the _______ planes? - ANSWER Octahedral planes
Another name for the cubic system - ANSWER Isometric
Polishes the crown and pavilion mains - ANSWER Blocker
Polishing of the star and upper and lower half facets - ANSWER Brillianteering
Bezel facets are the ones shaped like ____ - ANSWER Kites
Final Exam #2 with 194 correct solutions
Graded A+.
Star facets are the ones shaped like _____ next to the table - ANSWER Triangles
Upper half facets are the ones on the ______ next to the girdle - ANSWER Outer edge
Visible light is a form of - ANSWER Radiant energy
Grease on the pavilion of a diamond results in - ANSWER More light leakage through the pavilion
The rotary saw contributed to the diamond cutting industry by - ANSWER Allowing for greater weight retention from rough
A surface indentation with tiny, root-like feathers penetrating the stone is called a _____ - ANSWER Bruise
A stone with only a few extra facets on its pavilion that can't be seen face-up should be graded _____ - ANSWER Flawless
Diamonds with minute inclusions that range from difficult to very difficult to see under 10x are classified as - ANSWER VVS1 or VVS
Blemish; A small opening that looks like a tiny white dot at 10x - ANSWER Pit
An included diamond crustal that extends to the surface after fashioning - ANSWER Know
A long, thin crystal that looks like a tiny rod at 10x - ANSWER Needle
Final Exam #2 with 194 correct solutions
Graded A+.
Noticeable inclusions that are easy (SI1) or very easy (SI2) to see at 10x
- all inclusions are possible, grade depends on visibility - ANSWER Requirements for a SI1 and SI
Inclusions are obvious at 10x but can be seen without magnification
- inclusions seriously affect durability
- usually used for industrial purposes - ANSWER Requirements for I1, I2, and I
Green - blemishes
Red - inclusions
Red and Green - cavities, indented naturals, knots, etch channels, laser drill holes
Black - metal work from setting - ANSWER What do the colors on a plot mean?
Ia: abundant, plentiful nitrogen; near-colorless to yellow
Ib: rare, less nitrogen than Ia; more yellow than Ia
IIa: very rare, little to no nitrogen; colorless, brown, or gray
IIb: very rare, contains boron, little to no nitrogen; blue - ANSWER Diamond types
The relative lightness or darkness of a color - ANSWER Tone
A color's strength or intensity (ranging from dull to pure vivid) - ANSWER Saturation
The basic color of an object - ANSWER Hue
The care that goes into the fashioning of a polished diamond, as confirmed by its finish - ANSWER Craftsmanship
Final Exam #2 with 194 correct solutions
Graded A+.
A diamond's physical shape, including its proportions and durability, determined by decisions made during the fashioning process - ANSWER Design
The quality of the polish and precision of the cut of a fashioned gemstone - ANSWER Finish
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) - ANSWER The bowing method
60% - ANSWER Use the bowing method; If the lines are straight, the table % is about...
53% - ANSWER Use the bowing method; If the lines bow in noticeably, the table % is about...
58% - ANSWER Use the bowing method; If the lines bow in slightly, the table % is about...
63% - ANSWER Use the bowing method; If the lines bow out slightly, the table % is about...
67% - ANSWER Use the bowing method; If the lines bow out noticeably, the table % is about...
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 - ANSWER The flash method
Final Exam #2 with 194 correct solutions
Graded A+.
57.5-63% - ANSWER Excellent cut grades corresponding total depth % is...
56-64.5% - ANSWER Very good cut grades corresponding total depth % is...
53-66.5% - ANSWER Good cut grades corresponding total depth % is...
51-70.9% - ANSWER Fair cut grades corresponding total depth % is...
Less than 51% to greater than 70% - ANSWER Poor cut grades corresponding total depth % is...
Pavilion depth percentage - ANSWER Culet size should be considered when determining...
Larger - ANSWER As a diamond's pavilion gets deeper, its table reflection becomes...
True - ANSWER Naturals are a part of an evaluation proportion symmetry...True or False
Pavilions shallower than 38% - ANSWER In round brilliants, the girdle reflection (fisheye effect) becomes visible face-up at what pavilion depth?
Head, shoulder, belly, wing, point - ANSWER What are the parts of a pear shape?
Point, belly, wing, point - ANSWER What are the parts of a marquise shape?
Cleft, lobe, belly, wing, point - ANSWER What are the parts of a heart shape?
Final Exam #2 with 194 correct solutions
Graded A+.
(table size (measured across the width) / width) x 100
*round to the nearest 1% - ANSWER How do you calculate table % of a fancy-cut?
(depth/width) x 100
*round to the nearest tenth - ANSWER How do you calculate total depth of a fancy-cut?
(depth / AGD) x 100 - ANSWER How do you calculate total depth of a round brilliant?
59-63% or about 60% - ANSWER The normal range for total depth % on a round brilliant is...
YAG - ANSWER Which is harder? YAG or GGG?
GGG - ANSWER Which has higher dispersion (fire) YAG or GGG?
GGG - ANSWER Which has a higher specific gravity YAG or GGG?
Glass - ANSWER Diamond simulants called "paste" are...
Man-made diamond simulant
- singly refractive
- low hardness
- more dispersion than diamond - ANSWER Strontium titanate
Diamond simulant
- more dispersive than strontium titanate
- low hardness
Final Exam #2 with 194 correct solutions
Graded A+.
The price of a gem divided by its own carat weight - ANSWER Per-carat pricing
Table % = (average table diameter / AGD) x 100 - ANSWER How do you calculate table % for a round brilliant?
Use the distance btwn table edge and girdle at 100%
- if stars reach 1/3 of the way = 35%
- if stars reach 1/2 of the way = 50%
- if stars reach 2/3 of the way = 65%
- if stars reach 3/4 of the way = 75%
*Average all 8 estimations and round to the nearest 5% - ANSWER How do you estimate star length %?
Blemish - ANSWER Is a nick a blemish or an inclusion
An inclusion - ANSWER Is a chip a blemish or an inclusion?
