Assignment 7 - The path light travels

Question 1

The effect of all diamond’s internal and external reflections of white light

Answer 1

Brightness

Question 2

The flashes of color you see in a polished diamond

Answer 2

Fire

Question 3

The flashes of light and the contrasting dark areas you see when the diamond, the light or the observer moves

Answer 3

Scentillation

Question 4

The angles and relative measurements of a polished gem and the relationship between them

Answer 4

Proportions

Question 5

The bouncing back of light when it strikes a surface

Answer 5

Reflection

Question 6

The angle at which a ray of light strikes a surface, measured from the normal

Answer 6

Angle of incidence

Question 7

The angle between the normal and a reflected ray of light

Answer 7

Angle of reflection

Question 8

An imaginary line perpendicular to the point where a ray of light strikes the surface

Answer 8

Normal

Question 9

Change in speed and possible change in direction of light as it travels from one material to another

Answer 9

Refraction

Question 10

A measure of the change in the speed and the angle of light as it passes from one material to another

Answer 10

Refractive Index (RI)

Question 11

Angel between the normal and the maximum angle of refraction, which is the largest angle at which rays inside the diamond can escape

Answer 11

Critical angle

Question 12

An optical property that’s the difference between the RI values of specific violet and red wavelengths of visible light for a given material.

Answer 12

Dispersion

Question 13

The appearance of a material’s surface in reflected light.

Answer 13

Luster

Question 14

The highster degree of luster possible in a transparent material

Answer 14

Adamantine Luster

Question 15

Which proportions contribute the most to a diamond’s brightness?

Answer 15

Pavillion proportions

Question 16

What factors influence the amount of fire a diamond displays?

Answer 16

• the angle at which light enters a diamond
• number of times a light ray interacts iwth the internal facets
• factet junctions
• angle the light exits

Question 17

What are the two components of scintillation?

Answer 17

Sparkle (flashing spots of light) and pattern (of light and dark areas)

Question 18

The relative size, arrangement, and contrast of bright and dark areas that result from a diamond’s internal and external reflections.

Answer 18

Pattern

Question 19

What are the cut grades in the GIA system?

Answer 19

• Excellent
• Very good
• Good
• Fair
• Poor

Question 20

Why is proper lightning important to diamond cut grading?

Answer 20

Variations in lightning and surroundings can affect a diamond’s appearance.

Question 21

What type of lightning is preferable to grade a cut?

Answer 21

• Diffused fluorescent lightning helps to evaluate a diamond’s brightness and pattern.
• Spotlighting helps you evaluate its fire.

Question 22

The exactness of a finished gem’s shape and the placement of its facet

Answer 22

Symmetry

Question 23

The overall condition of the facet surfaces of a finished gem.

Answer 23

Polish

Question 24

What are diamond’s light performance attributes?

Answer 24

• Brightness
• Fire
• Scintillation

Question 25

What’s the critical angle of a diamond?

Answer 25

24.5 degrees

Question 26

Which pattern is caused by a shallow pavilion?

Answer 26

Fish-Eye

Question 27

Which pattern is caused by a deep pavilion?

Answer 27

Nailhead (Dark pattern)