Assignment 10 - Clarity

Question 1

Characteristic or irregularity confined to the surface of a polished gemstone.

Answer 1

Blemish

Question 2

How do inclusions and blemishes affect gemstone durability?

Answer 2

Some inclusions can affect durability. Breaks in a stone can threaten its structural integrity, especially if they reach the surface.

Question 3

How do inclusions and blemishes affect gemstone appearance?

Answer 3

They can have a dramatic effect on appearance. Some can reduce brilliance by disrupting the transmission of light through a gem.

The term inclusion can have negative meanings for some, but inclusions can contribute to the beauty of colored gemstones.

Question 4

How do inclusions and blemishes affect gemstone value?

Answer 4

Although they might affect appearance or durability, inclusions and blemishes seldom have a significant impact on a colored stone’s ultimate
value. Clarity characteristics that affect transparency and brilliance, or those that make a gem vulnerable to breaking, have the most influence on value.

Question 5

What are ten commonly seen inclusions?

Answer 5

• Included crystal & Negative crystal
• Needle & Silk
• Fingerprint & Feather
• Pinpoint & Cloud
• Cavity & Chip

Question 6

What are three commonly seen blemishes?

Answer 6

• Scratch
• Abrasion
• Polish lines

Question 7

A mineral crystal trapped within a gem as it grows.

Answer 7

Included crystal

Question 8

An angular, hollow space within a gem that resembles a mineral inclusion.

Answer 8

Negative crystal

Question 9

A long, thin inclusion that can be a solid crystal or a hollow tube that might be filled with liquid or gas.

Answer 9

Needle

Question 10

Group of fine needle-like inclusions.

Answer 10

Silk

Question 11

Inclusions that form a pattern that often resembles a human fingerprint.

Answer 11

Fingerprint

Question 12

A general term for a break in a stone.

Answer 12

Feather

Question 13

Any hazy or milky area that cannot be described as a feather, fingerprint, or group of included
crystals or needles.

Answer 13

Cloud

Question 14

Minute inclusion enclosed within a gem; can occur singly or in groups called clouds.

Answer 14

Pinpoint

Question 15

An opening that extends into a gem from the surface.

Answer 15

Cavity

Question 16

A damaged area on a gem, usually near the girdle.

Answer 16

Chip

Question 17

A linear scrape, normally seen as a fine curved or straight white line.

Answer 17

Scratch

Question 18

Tiny nicks and pits caused by wear and damage to a gem’s facet edges or culet.

Answer 18

Abrasions

Question 19

Tiny, parallel grooves on a facet surface left by the polishing operation.

Answer 19

Polish lines

Question 20

What factors determine a clarity characteristic’s influence on gem value?

Answer 20

• nature
• size
• number
• position
• relief

Question 21

What are the levels of clarity for colored stones?

Answer 21

1) Eye-clean
– no visible inclusions
2) Slightly included*
– Type I : minute inclusions
– Type II: minute or minor inclusions
– Type III: minute, minor or noticiable inclusions
3) Moderately included*
– Type I: minor inclusions
– Type II: noticiable inclusions
– Type III: obvious inclusions
4) Heavily included
– Prominent inclusions with negative effect on appearance, durability and value
5) Severely included
– Prominent inclusions with severe effect on appearance, durability and value

*Definition varies between Type I, II and III stones

Question 22

Contrast between an inclusion and its host gem.

Answer 22

Relief

Question 23

What are the three types (categories) of gem stones with respect to their typical clarity?

Answer 23

• Type I (typically eye-clean) - aquamarine; pink, green, and yellow beryl; chrysoberyl (excluding cat’s-eye); spodumene; green tourmaline; blue
  zircon; and tanzanite.
• Type II (typically visible inclusion that don’t affect beauty), anadusite, alexandrite, corundum (excluding stars), the transparent garnets, iolite, peridot, spinel, quartz, all colors of tourmaline except green and water-melon, and zircon.
• Type III (almost always included) - emerald, red beryl, and watermelon tourmaline.

Question 24

Why is your unaided eye an important tool for colored stone grading?

Answer 24

• Clarity characteristics that cannot be detected by the unaided eye will unlikely have a negative impact on the value of a colored stone.
• You might not have time to examine a stone with an instrument

Question 25

When might you use a loupe to judge an individual stone?

Answer 25

You should take the time to examine
expensive stones carefully with a loupe.

Question 26

How do you judge the clarity of gemstones in parcels?

Answer 26

1. evaluate its consistency of color, cut, clarity, and size. (don’t buy mixed or uncalibrated parcels)
2. take a sample selection and quickly look at color, brilliance, clarity, calibration, face-up outline, and pavilion depth.
3. assess value of parcel.

Question 27

Which of these clarity characteristics usually have the greatest impact on a gem’s marketability?

A. A cavity on its pavilion

B. A large, unhealed feather under its table

C. A small, dark crystal under its crown facets

D. A low-relief liquid inclusion under its table

Answer 27

B. A large, unhealed feather under its table

Question 28

Fingerprints are

A. pits.

B. fractures.

C. blemishes.

D. partially healed fracture planes.

Answer 28

D. partially healed fracture planes.

Question 29

Gems that are usually eye-clean include

A. peridot, spinel, and quartz.

B. ruby, alexandrite, and andalusite.

C. spodumene, yellow beryl, and aquamarine.

D. red beryl, emerald, and watermelon tourmaline.

Answer 29

C. spodumene, yellow beryl, and aquamarine.

Question 30

Growth zoning in a colored stone is evidence of

A. fashioning.

B. heat treatment.

C. crystal growth.

D. fracture filling.

Answer 30

C. crystal growth.