GIA Diamonds & Diamond Grading
Week 3 Practice Exam Questions &
Answers12
atom - ANSWERS-the basic structural unit of all matter
protons and neutrons form the nucleus while electrons surround the nucleus in orbits, or shells
- ANSWERS-What makes up an atom?
tetrahedron - ANSWERS-4 carbon atoms with 1 in the middle (total 5 carbon atoms)
formed from 4 tetrahedrons held together by shared electrons in strong covalent bonds -
ANSWERS-How is the core of a diamond's unit cell formed?
habit - ANSWERS-characteristic crystal shape or form of a mineral
octahedron - ANSWERS-What is a diamond's habit?
crystal structure or crystal lattice - ANSWERS-the regular, repeating arrangement of atoms in a
mineral
greatly affects a mineral's characteristics - ANSWERS-What does the crystal structure/crystal
lattice affect?
cleavage planes - ANSWERS-directions in which there are fewer carbon atoms, with more space
between them, than in others; planar surface along which a mineral tends to break due to
atomic weakness
, a flat break parallel to a cleavage plane - ANSWERS-What would a well-placed blow cause to a
cleavage plane?
cleavage - ANSWERS-a smooth, flat break in a crystal parallel to a cleavage plane
cubic crystal system - ANSWERS-What crystal system do diamonds belong to?
singly refractive or isotropic - ANSWERS-Because the cubic crystal system is the most
symmetrical, these crystals are described as...
cube, octahedron, & dodecahedron - ANSWERS-What are the 3 common crystal shapes of
minerals that form in a cubic system?
point defect - ANSWERS-an imperfection or deviation from the ideal arrangement of atoms in
relation to a single atom or point in the crystal lattice
intrinsic & extrinsic - ANSWERS-What are 2 types of point defects?
intrinsic defect - ANSWERS-a point defect created in diamond when a carbon atom is missing
from its original position—creating a vacancy—in the crystal lattice
extrinsic defect - ANSWERS-a point defect when diamonds incorporate atoms of elements not
part of their essential chemical composition, called trace elements, during formation
line defect (dislocations) - ANSWERS-imperfection or deviation from the ideal arrangement of
atoms in relation to a line in the crystal lattice
Week 3 Practice Exam Questions &
Answers12
atom - ANSWERS-the basic structural unit of all matter
protons and neutrons form the nucleus while electrons surround the nucleus in orbits, or shells
- ANSWERS-What makes up an atom?
tetrahedron - ANSWERS-4 carbon atoms with 1 in the middle (total 5 carbon atoms)
formed from 4 tetrahedrons held together by shared electrons in strong covalent bonds -
ANSWERS-How is the core of a diamond's unit cell formed?
habit - ANSWERS-characteristic crystal shape or form of a mineral
octahedron - ANSWERS-What is a diamond's habit?
crystal structure or crystal lattice - ANSWERS-the regular, repeating arrangement of atoms in a
mineral
greatly affects a mineral's characteristics - ANSWERS-What does the crystal structure/crystal
lattice affect?
cleavage planes - ANSWERS-directions in which there are fewer carbon atoms, with more space
between them, than in others; planar surface along which a mineral tends to break due to
atomic weakness
, a flat break parallel to a cleavage plane - ANSWERS-What would a well-placed blow cause to a
cleavage plane?
cleavage - ANSWERS-a smooth, flat break in a crystal parallel to a cleavage plane
cubic crystal system - ANSWERS-What crystal system do diamonds belong to?
singly refractive or isotropic - ANSWERS-Because the cubic crystal system is the most
symmetrical, these crystals are described as...
cube, octahedron, & dodecahedron - ANSWERS-What are the 3 common crystal shapes of
minerals that form in a cubic system?
point defect - ANSWERS-an imperfection or deviation from the ideal arrangement of atoms in
relation to a single atom or point in the crystal lattice
intrinsic & extrinsic - ANSWERS-What are 2 types of point defects?
intrinsic defect - ANSWERS-a point defect created in diamond when a carbon atom is missing
from its original position—creating a vacancy—in the crystal lattice
extrinsic defect - ANSWERS-a point defect when diamonds incorporate atoms of elements not
part of their essential chemical composition, called trace elements, during formation
line defect (dislocations) - ANSWERS-imperfection or deviation from the ideal arrangement of
atoms in relation to a line in the crystal lattice
