Diamonds 7 — The Diamond Crystal

Question 1

Another name for the cubic crystal system is

A.	isotropic.
B.	isometric.
C.	anisotropic.
D.	isomorphous.

Answer 1

B. isometric.

Question 2

Crystal shape is an important factor in the evaluation of rough because

A.	it influences the clarity grade.
B.	it often affects color and clarity.
C.	some crystal shapes are much softer than others.
D.	it affects the amount of weight retained after cutting.

Answer 2

D. it affects the amount of weight retained after cutting.

Question 3

The habit of gem-quality diamond is the

A.	cube.
B.	octahedron.
C.	dodecahedron.
D.	hexoctahedron.

Answer 3

B. octahedron.

Question 4

A flat, triangular twinned diamond crystal is called a

A.	macle.
B.	cleavage.
C.	splittable.
D.	tetrahedron.

Answer 4

A. macle.

Question 5

What is the specific gravity of gem-quality diamond?

A.	1.00
B.	2.17
C.	3.52
D.	4.01

Answer 5

C. 3.52

Question 6

The crystal planes most suitable for cleaving a diamond are the

A.	cubic planes.
B.	octahedral planes.
C.	dodecahedral planes.
D.	trisoctahedral planes.

Answer 6

B. octahedral planes.

Question 7

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

A.	trace elements.
B.	foreign elements.
C.	distortion impurities.
D.	irregularity elements.

Answer 7

A. trace elements.

Question 8

The smallest group of atoms with a characteristic chemical composition and the basic crystal structure of a mineral is called a(n)

A.	atom.
B.	unit cell.
C.	tetrahedron.
D.	building block.

Answer 8

B. unit cell.

Question 9

The strongest of all atomic bonds are called

A.	shells.
B.	covalent.
C.	magnetic.
D.	electrons.

Answer 9

B. covalent.

Question 10

Which is the softest crystal direction in diamond?

A.	Cubic
B.	Octahedral
C.	Hexahedral
D.	Dodecahedral

Answer 10

D. Dodecahedral

Question 11

In diamonds, cleavage is caused by

A.	variations in density.
B.	irregular atomic structure.
C.	octahedrons with points that are easily broken.
D.	relatively wide spaces between some atomic planes.

Answer 11

D. relatively wide spaces between some atomic planes.

Question 12

Squares or rectangles, trigons, and parallel grooves are types of

A.	macles.
B.	graining.
C.	twin crystals.
D.	growth marks.

Answer 12

D. growth marks.

Question 13

Solid matter with atoms arranged in a regular, repeating pattern is called a(n)

A.	rock.
B.	crystal.
C.	variety.
D.	element.

Answer 13

B. crystal.

Question 14

A naturally occurring, inorganic substance with a characteristic chemical composition and usually a characteristic crystal structure is known as a

A.	rock.
B.	crystal.
C.	variety.
D.	mineral.

Answer 14

D. mineral.

Question 15

The diamond term glassie refers to

A.	an aggregate mass.
B.	a well-formed octahedral crystal.
C.	a noticeably rounded hexoctahedron.
D.	a macle with an abundance of trigons.

Answer 15

B. a well-formed octahedral crystal.