GIA DIAMOND AND DIAMOND GRADING
EXAM 200 QUESTIONS AND CORRECT
ANSWERS WITH RATIONALES LATEST
UPDATES ALREADY GRADED A+|ASSURED
PASS!!!
Introduction
This practice exam consists of 200 multiple-choice questions covering the core
topics of the GIA Diamond and Diamond Grading curriculum. It is designed to
simulate the breadth and depth of the final exam, testing knowledge across
diamond formation, the 4Cs, clarity characteristics, treatments, synthetics,
simulants, and industry practices.
Each question includes four answer choices (A, B, C, D), the correct answer, and
a rationale explaining why that answer is correct. Questions are interchanged
across topics to reflect the integrated nature of the exam. No two questions are
duplicated.
Questions 1–50: Diamond Formation, Geology & Properties
1. Where do most gem-quality diamonds form?
A. In the Earth's crust, about 10 km deep
B. In the Earth's mantle, beneath ancient continental cratons
C. In oceanic subduction zones
D. In volcanic lava tubes near the surface
Correct Answer: B
Rationale: Most gem-quality diamonds crystallize in the mantle beneath ancient
,continental cratons at depths of roughly 150–200 km, where pressure and
temperature conditions are suitable.
2. What is the primary rock type that transports diamonds to the surface?
A. Granite
B. Basalt
C. Kimberlite
D. Limestone
Correct Answer: C
Rationale: Kimberlite, and less commonly lamproite, is the volcanic rock that
carries diamonds from the mantle to the surface in carrot-shaped pipes.
3. What are the approximate conditions required for diamond formation?
A. Low pressure, low temperature
B. High pressure, high temperature
C. High pressure, low temperature
D. Low pressure, high temperature
Correct Answer: B
Rationale: Diamonds require high pressure (about 45–60 kilobars) and high
temperature (about 900–1,300°C) to crystallize from carbon.
4. What is the chemical composition of diamond?
A. Silicon dioxide
B. Pure carbon
C. Aluminum oxide
D. Carbon and hydrogen
Correct Answer: B
Rationale: Diamond is composed of pure carbon atoms arranged in a rigid three-
dimensional crystal lattice.
,5. What is the crystal structure of diamond?
A. Hexagonal
B. Cubic
C. Trigonal
D. Monoclinic
Correct Answer: B
Rationale: Diamond crystallizes in the cubic system, most commonly as
octahedra, and its cubic structure contributes to its extreme hardness.
6. What is the hardness of diamond on the Mohs scale?
A. 7
B. 8
C. 9
D. 10
Correct Answer: D
Rationale: Diamond is the hardest known natural mineral, ranking 10 on the Mohs
scale.
7. Diamond's hardness is best described as:
A. Equal in all directions
B. Directional, varying by crystallographic direction
C. Greatest along the cube face
D. Unrelated to crystal structure
Correct Answer: B
Rationale: Diamond is hardest along the octahedral plane and softer along other
directions, which is why it can be cleaved along octahedral planes.
8. What is the specific gravity of diamond?
A. 2.65
B. 3.52
, C. 4.00
D. 2.42
Correct Answer: B
Rationale: Diamond has a specific gravity of approximately 3.52, which helps
distinguish it from simulants like quartz (2.65) and CZ (5.60–5.95).
9. What is the refractive index of diamond?
A. 1.54
B. 1.76
C. 2.42
D. 2.65
Correct Answer: C
Rationale: Diamond's single refractive index is 2.42, which is very high and
contributes to its brilliance.
10. Diamond is:
A. Singly refractive
B. Doubly refractive
C. Optically isotropic
D. Both A and C
Correct Answer: D
Rationale: Diamond is cubic and therefore singly refractive (isotropic); it does not
split light into two rays.
11. What is the dispersion (fire) of diamond?
A. 0.044
B. 0.104
C. 0.020
D. 0.170
EXAM 200 QUESTIONS AND CORRECT
ANSWERS WITH RATIONALES LATEST
UPDATES ALREADY GRADED A+|ASSURED
PASS!!!
Introduction
This practice exam consists of 200 multiple-choice questions covering the core
topics of the GIA Diamond and Diamond Grading curriculum. It is designed to
simulate the breadth and depth of the final exam, testing knowledge across
diamond formation, the 4Cs, clarity characteristics, treatments, synthetics,
simulants, and industry practices.
Each question includes four answer choices (A, B, C, D), the correct answer, and
a rationale explaining why that answer is correct. Questions are interchanged
across topics to reflect the integrated nature of the exam. No two questions are
duplicated.
Questions 1–50: Diamond Formation, Geology & Properties
1. Where do most gem-quality diamonds form?
A. In the Earth's crust, about 10 km deep
B. In the Earth's mantle, beneath ancient continental cratons
C. In oceanic subduction zones
D. In volcanic lava tubes near the surface
Correct Answer: B
Rationale: Most gem-quality diamonds crystallize in the mantle beneath ancient
,continental cratons at depths of roughly 150–200 km, where pressure and
temperature conditions are suitable.
2. What is the primary rock type that transports diamonds to the surface?
A. Granite
B. Basalt
C. Kimberlite
D. Limestone
Correct Answer: C
Rationale: Kimberlite, and less commonly lamproite, is the volcanic rock that
carries diamonds from the mantle to the surface in carrot-shaped pipes.
3. What are the approximate conditions required for diamond formation?
A. Low pressure, low temperature
B. High pressure, high temperature
C. High pressure, low temperature
D. Low pressure, high temperature
Correct Answer: B
Rationale: Diamonds require high pressure (about 45–60 kilobars) and high
temperature (about 900–1,300°C) to crystallize from carbon.
4. What is the chemical composition of diamond?
A. Silicon dioxide
B. Pure carbon
C. Aluminum oxide
D. Carbon and hydrogen
Correct Answer: B
Rationale: Diamond is composed of pure carbon atoms arranged in a rigid three-
dimensional crystal lattice.
,5. What is the crystal structure of diamond?
A. Hexagonal
B. Cubic
C. Trigonal
D. Monoclinic
Correct Answer: B
Rationale: Diamond crystallizes in the cubic system, most commonly as
octahedra, and its cubic structure contributes to its extreme hardness.
6. What is the hardness of diamond on the Mohs scale?
A. 7
B. 8
C. 9
D. 10
Correct Answer: D
Rationale: Diamond is the hardest known natural mineral, ranking 10 on the Mohs
scale.
7. Diamond's hardness is best described as:
A. Equal in all directions
B. Directional, varying by crystallographic direction
C. Greatest along the cube face
D. Unrelated to crystal structure
Correct Answer: B
Rationale: Diamond is hardest along the octahedral plane and softer along other
directions, which is why it can be cleaved along octahedral planes.
8. What is the specific gravity of diamond?
A. 2.65
B. 3.52
, C. 4.00
D. 2.42
Correct Answer: B
Rationale: Diamond has a specific gravity of approximately 3.52, which helps
distinguish it from simulants like quartz (2.65) and CZ (5.60–5.95).
9. What is the refractive index of diamond?
A. 1.54
B. 1.76
C. 2.42
D. 2.65
Correct Answer: C
Rationale: Diamond's single refractive index is 2.42, which is very high and
contributes to its brilliance.
10. Diamond is:
A. Singly refractive
B. Doubly refractive
C. Optically isotropic
D. Both A and C
Correct Answer: D
Rationale: Diamond is cubic and therefore singly refractive (isotropic); it does not
split light into two rays.
11. What is the dispersion (fire) of diamond?
A. 0.044
B. 0.104
C. 0.020
D. 0.170
