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GIA DIAMONDS AND DIAMOND GRADING FINAL EXAM 2025
LATEST UPDATED | ALREADY GRADED A+
What group was critical to De Beers's early sales strategy? CORRECT ANSWER >>>London Diamond Syndicate How are gem-quality rough diamonds sorted? CORRECT ANSWER >>>Color What generation was first to connect with diamonds as a representation of lifetime commitment? CORRECT ANSWER >>>Baby Boomers Where did the diamond industry first start? CORRECT ANSWER >>>India What describes the concept of centrally controlled supply, purchase, promotion, and sales of rough diamonds? CORRECT ANSWER >>>Single-channel marketing What mantle layer is most dense? CORRECT ANSWER >>>Lower mantle What happens to diamond if lamproite stalls in the continental crust? CORRECT ANSWER >>>Will turn into graphite When does subduction occur? CORRECT ANSWER >>>When a continental and oceanic plate collide How are metamorphic rocks formed? CORRECT ANSWER >>>High heat and high pressure What is an example of a superdeep diamond? CORRECT ANSWER >>>CLIPPIR diamonds, blue diamonds, Brazil's Junia diamond What might black spinel in a mineral sample indicate? CORRECT ANSWER >>>A good sign that a pipe is nearby What equipment might offshore deep-sea diamond mining use? CORRECT ANSWER >>>Robotic/automated crawlers What deposit type produces most diamonds mined today? CORRECT ANSWER >>>Primary deposits What type of sampling gives an initial idea of diamond quality for a deposit? CORRECT ANSWER >>>Character sampling
Where are rocks and geological structures similar to Africa found due to ancient connections? CORRECT ANSWER >>>Brazil What is another term for crystal lattice? CORRECT ANSWER >>>Crystal structure What type are most natural diamonds? CORRECT ANSWER >>>Type Ia What is a smooth, flat break in a crystal parallel to a cleavage plane? CORRECT ANSWER >>>Cleavage What is a flat, triangular, twinned diamond crystal? CORRECT ANSWER >>>Macle What types of point defects are found in diamonds? CORRECT ANSWER >>>Intrinsic defect and extrinsic defects What influences light absorption, resulting in bodycolor? CORRECT ANSWER >>>Color center What trace element can cause a violet color in diamonds? CORRECT ANSWER >>>Hydrogen-related defects How does the energy emitted by a gem compare to the energy it absorbs? CORRECT ANSWER >>>Lower What type of light combines all the colors in the visible spectrum? CORRECT ANSWER >>>White light What is the most common cause of yellow color in diamonds? CORRECT ANSWER >>>Nitrogen defects What controls light path length within a diamond? CORRECT ANSWER >>>Cutting What term describes a gemstone's surface in reflected light? CORRECT ANSWER >>>Luster What describes the flashes of spectral colors seen in a polished diamond? CORRECT ANSWER >>>Fire What was the main goal of research in developing the GIA Cut Grading System? CORRECT ANSWER >>>Determine which proportion combinations create the most attractive light performance What best describes the angle of incidence? CORRECT ANSWER >>>Measured btwn the normal and the reflected light What process splits diamond rough along its cleavage plane? CORRECT ANSWER >>>Cleaving What do cutters evaluate to determine when to use a scaife for coning? CORRECT ANSWER >>>Strain What made true round-shaped diamonds possible? CORRECT ANSWER >>>Bruting
What is a sieve set? CORRECT 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? CORRECT ANSWER >>>Sharpens spectral absorption peaks and allows gemologists to identify the optical defects in the diamond What can UV-Vis-NIR spectroscopy help identify? CORRECT 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? CORRECT ANSWER >>>Terms of payment What is the per-carat price of a 2ct diamond selling for $40,000? CORRECT ANSWER >>>$20, What parcel price comes at a premium? CORRECT ANSWER >>>Pick price How do dealers quote diamond prices? CORRECT ANSWER >>>Per-carat price What is the term for flaws or imperfections in a diamond? CORRECT ANSWER >>>Inclusions What can help determine a clarity characteristics location? CORRECT ANSWER >>>Loupe/microscope What clarity characteristic is found only on the surface of a gemstone? CORRECT ANSWER >>>Blemishes What clarity characteristic results when a crystal is expelled? CORRECT ANSWER >>>Cavity Where are inclusions most visible? CORRECT ANSWER >>>Directly under the table What kind of clarity characteristic is not seen at 10x mag.? CORRECT ANSWER >>>Cloud or pinpoint What describes the contrast btwn an inclusion and the diamond? CORRECT ANSWER >>>Relief What best describes the clarity characteristics in SI1 and SI2 stones? CORRECT ANSWER >>>Noticeable inclusions that are very easy to see at 10x mag. Where is a feather that reaches both the crown and pavilion plotted? CORRECT ANSWER >>>Plotted on both the crown and pavilion diagrams What is a term that describes tone? CORRECT ANSWER >>>Degree of darkness or lightness What color becomes more prominent as cool hues become less saturated? CORRECT ANSWER >>>Gray
What term falls on the GIA D-to-Z color scale? CORRECT ANSWER >>>Light What material are masterstones? CORRECT ANSWER >>>Diamonds What position are colored diamonds color graded in? CORRECT ANSWER >>>Face-up Where is the focus when color grading a heavily included diamond? CORRECT ANSWER >>>The least included area How do you measure a diamond's depth? CORRECT 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? CORRECT ANSWER >>> What weight retention method can change the balance of the diamond's face-up pattern? CORRECT ANSWER >>>Painting What facet forms the pavilion angle when it meets the girdle plane? CORRECT ANSWER >>>Pavilion What pavilion depth percentage might reflect the girdle face-up through the table? CORRECT ANSWER >>>37% Why do diamonds with thick girdles offer less value? CORRECT ANSWER >>>Paying for more weight than you see What might be found in a diamond with misalignment (Aln)? CORRECT ANSWER >>>Misshapen facets How do shallow pavilion angles affect appearance? CORRECT ANSWER >>>Make it look foggy What style describes a diamond that has both brilliant-cut and step-cut facets? CORRECT ANSWER >>>Mixed cut What is the area between the head and belly of an oval? CORRECT ANSWER >>>Shoulders What is used for total depth percentage calculation in fancy shapes? CORRECT ANSWER >>>Width of stone (instead of average girdle diameter) Why is there no single cut grading standard for fancy cuts? CORRECT ANSWER >>>Too many variations What style helps avoid point breakage in fancy cuts? CORRECT ANSWER >>>French tip
The deep vertical formations through which diamonds traveled to the surface CORRECT ANSWER >>>Pipes An older underground mining technique
- expensive and dangerous (no longer used)
- block caving is the alternative to this CORRECT ANSWER >>>Chambering Most of the diamonds that come from Africa are recovered from _______ deposits CORRECT ANSWER >>>Pipe, alluvial, and marine deposits Most of the diamonds that come from Russia are recovered from ______ sources. CORRECT ANSWER >>>Primary sources What is the specific gravity of a gem-quality diamond? CORRECT ANSWER >>>3. Diamonds are more concentrated in which type of deposit? CORRECT ANSWER >>>Marine deposits The first step in exploring for diamonds is to _____ CORRECT ANSWER >>>Look for the oldest parts of the earths crust The diamond industry has changed dramatically in recent years because _____ CORRECT 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 _____ CORRECT ANSWER >>>India What is the softest crystal direction in diamond? CORRECT ANSWER >>>Dodecahedral What crystal structure does diamond belong to? CORRECT ANSWER >>>Isometric or cubic crystal structure What are diamond's 3 internal crystal planes? CORRECT ANSWER >>>Cubic (runs horizontal), octahedral (on face), dodecahedral (runs vertical) The crystal planes most suitable for cleaving a diamond are the _______ planes? CORRECT ANSWER >>>Octahedral planes Another name for the cubic system CORRECT ANSWER >>>Isometric
Polishes the crown and pavilion mains CORRECT ANSWER >>>Blocker Polishing of the star and upper and lower half facets CORRECT ANSWER >>>Brillianteering Bezel facets are the ones shaped like ____ CORRECT ANSWER >>>Kites Star facets are the ones shaped like _____ next to the table CORRECT ANSWER >>>Triangles Upper half facets are the ones on the ______ next to the girdle CORRECT ANSWER >>>Outer edge Visible light is a form of CORRECT ANSWER >>>Radiant energy Grease on the pavilion of a diamond results in CORRECT ANSWER >>>More light leakage through the pavilion The rotary saw contributed to the diamond cutting industry by CORRECT ANSWER >>>Allowing for greater weight retention from rough A surface indentation with tiny, root-like feathers penetrating the stone is called a _____ CORRECT ANSWER >>>Bruise A stone with only a few extra facets on its pavilion that can't be seen face-up should be graded _____ CORRECT ANSWER >>>Flawless Diamonds with minute inclusions that range from difficult to very difficult to see under 10x are classified as CORRECT ANSWER >>>VVS1 or VVS Blemish; A small opening that looks like a tiny white dot at 10x CORRECT ANSWER >>>Pit An included diamond crustal that extends to the surface after fashioning CORRECT ANSWER >>>Know A long, thin crystal that looks like a tiny rod at 10x CORRECT ANSWER >>>Needle A very small included crystal that looks like a tiny dot at 10x CORRECT ANSWER >>>Pinpoint Many tightly grouped pinpoints CORRECT ANSWER >>>Cloud A series of pinpoints, clouds, or crystals that form in the diamond's growth plane CORRECT ANSWER >>>Twinning wisp Size, number, location, relief, nature CORRECT ANSWER >>>The five clarity factors No inclusions or blemishes under 10x can have these features:
Black - metal work from setting CORRECT 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 CORRECT ANSWER >>>Diamond types The relative lightness or darkness of a color CORRECT ANSWER >>>Tone A color's strength or intensity (ranging from dull to pure vivid) CORRECT ANSWER >>>Saturation The basic color of an object CORRECT ANSWER >>>Hue The care that goes into the fashioning of a polished diamond, as confirmed by its finish CORRECT ANSWER >>>Craftsmanship A diamond's physical shape, including its proportions and durability, determined by decisions made during the fashioning process CORRECT ANSWER >>>Design The quality of the polish and precision of the cut of a fashioned gemstone CORRECT 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) CORRECT ANSWER >>>The bowing method 60% CORRECT ANSWER >>>Use the bowing method; If the lines are straight, the table % is about... 53% CORRECT ANSWER >>>Use the bowing method; If the lines bow in noticeably, the table % is about... 58% CORRECT ANSWER >>>Use the bowing method; If the lines bow in slightly, the table % is about... 63% CORRECT ANSWER >>>Use the bowing method; If the lines bow out slightly, the table % is about...
67% CORRECT 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 CORRECT ANSWER >>>The flash method Used to estimate table %
- imagine a line from girdle to star facet (line A) and a line from star facet to center of stone where culet is (line B) *A is always 1
- 1:1 = 54%
- 1:1 1/4 = 60%
- 1:1 1/2 = 65%
- 1: 1 3/4 = 69%
- 1:2 = 72% CORRECT ANSWER >>>The ratio method 54% CORRECT ANSWER >>>Use the ratio method; If lines A and B are 1:1, the table % is about... 60% CORRECT ANSWER >>>Use the ratio method; If lines A and B are 1:1 1/4, the table % is about... 65% CORRECT ANSWER >>>Use the ratio method; If lines A and B are 1:1 1/2, the table % is about... 69% CORRECT ANSWER >>>Use the ratio method; If lines A and B are 1:1 3/4, the table % is about... 72% CORRECT ANSWER >>>Use the ratio method; If lines A and B are 1:2, the table % is about...
- the flash method
- the ratio method
59 - 63% or about 60% CORRECT ANSWER >>>The normal range for total depth % on a round brilliant is... YAG CORRECT ANSWER >>>Which is harder? YAG or GGG? GGG CORRECT ANSWER >>>Which has higher dispersion (fire) YAG or GGG? GGG CORRECT ANSWER >>>Which has a higher specific gravity YAG or GGG? Glass CORRECT ANSWER >>>Diamond simulants called "paste" are... Man-made diamond simulant
- singly refractive
- low hardness
- more dispersion than diamond CORRECT ANSWER >>>Strontium titanate Diamond simulant
- more dispersive than strontium titanate
- low hardness
- doubly refractive
- no longer used CORRECT ANSWER >>>Synthetic rutile Thermal conductivity CORRECT ANSWER >>>The easiest way to separate diamond from synthetic cubic zirconia is by checking for... Doubling CORRECT ANSWER >>>The easiest way to separate diamond from synthetic moissanite is by checking for... Proportions (shape-appeal factor) CORRECT ANSWER >>>On an emerald-cut diamond, very narrow corners should be noted under... Have much larger critical angles CORRECT ANSWER >>>Some diamond simulants display "see-through" because, compared to a diamond, they... Waxy to granular surface CORRECT ANSWER >>>Diamond's girdle surface is usually a...
Is limited by high production costs CORRECT ANSWER >>>The use of lab-grown diamonds in jewelry... Etched or frosted naturals CORRECT ANSWER >>>What is an indication of the HPHT treatment? A machine used to accelerate electrons to high energy along a straight path
- it is used to color treat diamonds to produce blue or blue-green color CORRECT ANSWER >>>Linear accelerator and what is it used for Using heat to stabilize irradiated color in gemstones
- when used following irradiation (2-step process) it produces brown, orange, or yellow and can rarely produce pink, red, or purple CORRECT ANSWER >>>Annealing The price of a gem divided by its own carat weight CORRECT ANSWER >>>Per-carat pricing Table % = (average table diameter / AGD) x 100 CORRECT 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% CORRECT ANSWER >>>How do you estimate star length %? Blemish CORRECT ANSWER >>>Is a nick a blemish or an inclusion An inclusion CORRECT ANSWER >>>Is a chip a blemish or an inclusion?
