Assignment 8 - Color

Question 1

What are the three components of bodycolor?

Answer 1

• Hue
• Tone
• Saturation

Question 2

How does the trade use special terms to describe gem color?

Answer 2

Trade terms connect certain words with particular gemstone colors or geographic locations.

Question 3

The selection of colors in which a gemstone occurs.

Answer 3

Color range

Question 4

The color or colors in a gemstone’s color range considered by the trade to be the most desirable.

Answer 4

Fine color

Question 5

A gemstone’s basic color, determined by its selective absorption of light.

Answer 5

Bodycolor

Question 6

The first impression of an object’s basic color.

Answer 6

Hue

Question 7

Degree of darkness or lightness of a color.

Answer 7

Tone

Question 8

A color’s strength or intensity.

Answer 8

Saturation

Question 9

Terms often used in the jewelry industry to describe particular gemstone colors or link gems with specific geographic locations.§§

Answer 9

Trade terms

Question 10

How does a gemstone’s cut influence its face-up color?

Answer 10

Every piece of rough has its own unique pattern of color distribution, which is the amount of color
and its location in the crystal.

Question 11

What causes windows?

Answer 11

Shallow cutting results in loss of light. Light entering the stone’s crown from above meets the pavilion facets at the wrong angle and exits the stone without being reflected back to the eye. And because the pavilion is shallow, light from below travels through the pavilion and exits through the crown. Because the light has only a short distance to travel through the stone, the color is less intense than if the stone were cut to excellent proportions.

Question 12

What causes extinction?

Answer 12

Extinction is a result of the cutting process, and all stones display some extinction at some viewing angles. Light enters the crown facets, reflects off one side of the pavilion, and escapes through the other side of the pavilion instead of through the crown.

Question 13

How do color zoning and pleochroism influence a gem’s color or appearance?

Answer 13

Depending on how the gems are cut they might have a visible impact on the color of the gem and influence its value.

Question 14

How does clarity affect a stone’s color?

Answer 14

Fine inclusions can scatter light within a faceted
stone and make extinction much less noticeable. Stones with a slightly diffused, or “sleepy,” appearance, like some sapphires, show this effect. Inclusions can also give a gem its color. Bright particles of green mica give aventurine quartz its green bodycolor, and inclusions of brownish hematite add depth to the color of some yellow sapphires.

Question 15

How does fluorescence affect a stone’s color?

Answer 15

Fluorescence adds an extra glow to red spinel’s appearance. It also boosts the red bodycolor of chromium-rich rubies, sometimes enough to
counteract extinction.

Question 16

An area of weak saturation in a transparent gemstone’s bodycolor that usually results from
the way the gem was cut.

Answer 16

Window

Question 17

Dark areas in a faceted transparent colored stone.

Answer 17

Extinction

Question 18

Light that exits through the pavilion in an
uncontrolled way due to compromises in a gem’s proportions.

Answer 18

Unplanned light leakage

Question 19

Light that exits through a gem’s crown in a
controlled way due to the correct proportions of its cut.

Answer 19

Planned light leakage

Question 20

Areas of different color in a gem, caused by variations in growth conditions.

Answer 20

Color zoning

Question 21

Visible face-up color zoning that the cutter
was unable to conceal.

Answer 21

Unintended color zoning

Question 22

Visible face-up color zoning that was planned during the cutting process.

Answer 22

Intended color zoning

Question 23

What should you look for when judging a gem’s color?

Answer 23

• Is the stone light, medium, or dark in tone?
• What is the gem’s bodycolor?
• Is the saturation weak, moderate, strong, or vivid?
• Is the stone’s color exceptional or poor for that gem species?

Question 24

What conditions are important for effective color grading?

Answer 24

One of the most important aspects of buying and grading colored stones is the type of lighting you use. For consistency, you should view colored
stones under daylight-equivalent fluorescent lighting whenever possible.

Question 25

What steps should you take to grade a colored stone?

Answer 25

• Clean Stone
• Hold against white/neutral background
• Evaluate the tone
• Assess bodycolor and identify hue.
• Consider the saturation