Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

GIA Graduate Gemologist - GEM 230 > Assignment 5 - The Diamond Crystal > Flashcards

Assignment 5 - The Diamond Crystal Flashcards

1
Q

Solid matter with atoms arranged in a regular, repeating order

A

Crystal

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Composed of crystals or related to crystals

A

Crystalline

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

The basic structural unit of all matter.

A

Atom

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

How do carbon atoms combine to build a diamond crystal?

A

Neighbouring atoms share electrons and form a “covalent bond”. Covalent bonds are the strongest of all atomic bonds. Diamond’s atoms are more closely bonded than the atoms of any other natural element.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is a diamond’s characteristic crystal shape?

A

The most common habit of a gem diamond is the octahedron, but perfectly shaped octahedral rough is rare.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

A chemical bond formed by two atoms sharing electrons

A

Covalent Bond

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

In a diamond, a group of five carbon atoms with one at the center.

A

Tetrahedron

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Smallest group of atoms with the characteristic composition and the basic crystal structure of a mineral.

A

Unit cell

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Geometric shape of a well-formed crystal

A

Crystal shape (form)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Characteristic crystal shape of a specific mineral

A

Habit

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

A form with eight equal triangular faces.

A

Octahedron

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

A well-shaped, transparent, octahedral diamond crystal with sharp, square edges.

A

Glassie

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Regular, repeating arrangement of atoms in a mineral

A

Crystal structure (lattice)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Categories of crystals based on their symmetry and internal structure.

A

Crystal systems

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Which crystal system does Diamond form in?

A

Cubic.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is the specific gravity of a diamond?

A

3.52

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Possessing the same physical or optical properties in all crystal directions

A

Singly refractive (isotropic)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Possessing different physical or optical properties in different crystal directions

A

Doubly refractive (anisotropics)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

The appearance of double images of a gemstone’s facet junction on the side opposite the viewer

A

Doubling

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

An imperfection or deviation from the ideal crystal lattice

A

Defect

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What are the categories of crystal lattice defects in a diamond crystal?

A

The three categories of defects are:
- point (intrinsic & extrinsic)
- line
- volume

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Defect in relation to a single atom in the crystal lattice.

A

Point defect.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

A (intrinsic) point defect when an atom is missing from it original position in the lattice.

A

Vacancy.

24
Q

Atoms in a gem that aren’t part of its essential chemical composition

A

Trace elements.

25
Q

Defect in relation to a line in the crystal lattice

A

Line defect

26
Q

The force required to produce distortion in the crystal lattice

A

Stress

27
Q

The plane or surface in which a dislocation travels through the crystal to cause an offset

A

Glide plane

28
Q

Defects caused by a three-dimensional aggregate of atoms or vacancies within the crystal lattice

A

Volume defect.

29
Q

Distortion or deformation in a crystal

A

Strain

30
Q

Visible, shadow-like lines in a diamond caused by irregularities in the crystal structure.

A

Graining (grain lines)

31
Q

How do dislocations contribute to strain in a diamond crystal?

A

The more dislocations that occur in a crystal, the more strain the crystal bears.

32
Q

What is the foundation of the diamond type classification system?

A

The presence or absence of nitrogen and boron atoms and the way they are arranged in the crystal lattice.

33
Q

What diamond types are rarely found in nature?

A

Type Ib (with isolated nitrogen imppurities). Most are Ia.

34
Q

How does a diamond’s crystal structure dictate cutting methods?

A

The cleavage planes (cubic, octahedral, dodecahedral) are the most important directions to a diamond cutter.

35
Q

What are diamond’s basic crystal shapes and planes?

A
  • Cubic
  • Octahedral
  • Dodecahedral
36
Q

How is diamond rough evaluated for cutting?

A

Diamond rough’s potential as a faceted gem depends on its shape, clarity and color.

Shape is the most important factor in a rough gem diamond crystal’s potential value.

Inclusions can limit a rough diamond’s potential shape.

37
Q

Capacity of a material to expand when it’s heated

A

Thermal expansion

38
Q

The relative ability of a material to transfer heat

A

Thermal conductivity

39
Q

Plane parallel to a possible crystal face, where a diamond can split clearly when struck.

A

Cleavage plane

40
Q

Crystal consisting of two or more intergrown crystals with opposing crystal directions.

A

Twinned crystal

41
Q

A flat, triangular twinned diamond crystal.

A

Macle

42
Q

A solid mass of individual, randomly oriented crystals, inter-grown and held together by a natural binding agent.

A

Aggregate

43
Q

How are nitrogen atoms arranged in the diamond crystal lattice when diamonds first form?

A

Isolated.

44
Q

What is the only way to accurately determine diamond type?

A

Spectroscopy

45
Q

How many directions of cleavage does diamond have?

A

Four.

46
Q

Which type of growth mark indicates an octahedral crystal face in diamond?

A

Trigons.

47
Q

What can cause a combination of octahedral and dodecahedral crystal forms?

A

Resorption

48
Q

The process in which the outer surface of a diamond is partially dissolved during transport.

A

Resorption

49
Q

What is the most important value factor for cuttable rough diamond?

A

Shape

50
Q

What is a shallow diamond crystal with limited potential shape?

A

Flat

51
Q

How many tetrahedrons form the core of a diamond’s unit cell?

A

4

52
Q

How do you distinguish Type I from Type II diamonds

A

Type I contains Nitrogen impurities.

Type II do not contain significant Nitrogen impurities.

53
Q

How do you distinguish Type Ia from Type Ib diamonds?

A

Both have Nitrogen impurities.

Type Ia have aggregated Nitrogen impurities. (a=aggregate)

Type Ib have isolated Nitrogen impurities.

54
Q

How do you distinguish Type IIa from Type IIb Diamonds

A

Type IIb diamonds contain Boron impurities. (b = boron)

55
Q

What is another name for the cubic system?

A

Isometric

GIA Graduate Gemologist - GEM 230 (20 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions