GIA JUNIOR GEMOLOGIST PROGRAM
TM
Table of Contents
About GIA..........................................................................................1
Geology and Gems..........................................................................3
What Is a Rock? ..............................................................................4
Rock Cycle—New Rocks from Old ..............................................5
Minerals ............................................................................................7
What Is a Mineral? ..........................................................................8
Mohs Scale of Hardness ............................................................10
Mohs Scale of Hardness Worksheet ........................................11
Gemology ......................................................................................12
What Is a Gem? ............................................................................13
Inclusions ......................................................................................14
Phenomena....................................................................................16
Looking at Phenomena Worksheet ..........................................17
Tools of the Trade ........................................................................18
Gemstone Inclusion Activity ......................................................20
Birthstones and Lore ..................................................................21
Word Search ..................................................................................25
Crossword Puzzle ........................................................................26
Glossary of Terms ........................................................................27
Some words in this book are bold. These
words have definitions in the glossary at
the end of the book.
Welcome!
Dear GIA Junior Gemologists,
The Gemological Institute of America welcomes you!
Today you will get a glimpse into the amazing world
of gemology. You’ll learn what we do at GIA and
what makes the study of gems so fascinating. You’ll
get to look inside gemstones using the tools of the
trade and see for yourself what makes each gem
unique.
We’re certain your time with us will be exciting, and
we hope it’s just the start of a life-long interest in
gems and gemology.
Enjoy your experience and please come back and see
us again.
Sincerely,
Guest Services
GIA World Headquarters and
The Robert Mouawad Campus
5345 Armada Drive
Carlsbad, CA 92008
T 800 421 7250
T 760 603 4000, ext 4116
F 760 603 4199
E [email protected]
www.gia.edu
About GIA
We’re a school. We’re a laboratory. Many scientists and
teachers work here. We’ve been teaching students gemology
(the study of gemstones), developing equipment, and setting
standards in the gem and jewelry industry since 1931.
People come from all over the world to study at GIA. They
want to work in the gem and jewelry industry. We teach
people how to identify and evaluate gems. And we teach
them how to design and make jewelry.
We have the world’s largest gemological library. It’s called
the Richard T. Liddicoat Gemological Library and Information
Center. We collect and preserve books about gems and
jewelry. We have over 38,000 books. Our oldest one dates
back to 1496.
We also collect and preserve mineral specimens, jewelry,
gem art, and gemological equipment.
We have beautiful gems on display at our schools around
the world.
T o p left , G I A M u seu m ;
to p r igh t , G I A L ib r a r y ;
b o tto m , G I A stu d en t s
1
2
Geology and Gems
Geology is the science and study of the earth.
The forces shaping the earth’s surface build and wear down
huge mountain chains over millions of years. They crush,
melt, and change vast volumes of rock. And every time heat
and pressure force rocks to change, gems might form.
Geology helps gem prospectors decide where to look for
new gem sources. They know that certain gem deposits
are associated with certain types of rock. This helps them
narrow down the search for gems.
F a cin g p a ge, ice r o a d tr u ck s ta k in g su p p lies to a d i a m o n d m in e in
n o r th er n C a n a d a ; a b o v e, em er a ld r o u gh fr o m th e C o sq u ez m in e
in C o lo m b i a , p ictu r ed r igh t .
Someone who studies geology is
called a
3
What Is a Rock?
Rocks are a combination of minerals and are the building
blocks of the earth. They tell a story about the earth and how it
was formed. Some rocks form at or near the earth’s surface
and others form deep in the earth’s crust or in the middle layer
of the earth called the mantle.
Although there are many kinds of rocks, geologists classify
them into three groups based on how they’re formed:
Igneous rocks, such as lava, obsidian, pumice, and granite,
start out in a molten or semi-molten state and become solid
when they cool.
©iS to ck p h o to .co m / t w in k lesta r 2
Sedimentary rocks, like sandstone, shale, and limestone, are
formed by layers of sediments squeezed and pressed together
over a long period of time.
Metamorphic rocks, such as slate, schist, and marble, have
their makeup, texture, or structure changed by great heat,
pressure, or both.
Name a rock that forms
by each process:
1. Igneous
2. Sedimentary
3. Metamorphic
©iS to ck p h o to .co m / sier r a r a t
4
Rock Cycle—
New Rocks from Old
metamorphic
The rock cycle is a recycling process that never stops. It
makes new rocks from old ones. If the rocks are deep
underground, they’re altered or melted by the earth’s inner
forces. If they’re at the surface, weathering—exposure to
water, wind, and other environmental conditions—breaks
them down. Erosion may move the rocks far from their original location. The broken-down rocks are buried, altered by
pressure, or melted by high temperatures to begin the cycle
again.
igneous
sedimentary
crust
mantle
5
L eft , t a lc cr y st a l; r igh t , m o r ga n ite (b er yl) cr y st a l
6
Minerals
If rocks are the building blocks that make up the earth, then
minerals are the stuff that rocks are made of.
Mineralogy is the study of minerals and how they’re formed.
A person who studies mineralogy is
called a
R ich a r d T . L id d ico a t
7
What Is a Mineral?
First of all, minerals must be solid. They can’t be gases or
liquids.
Second, minerals have never been alive—they’re inorganic.
Inorganic materials are composed of non-living matter. They’re
different from organic materials, like coral or ivory, that are
made by or come from living organisms.
Minerals are made by nature, not by human hands. A
mineral can’t be made by scientists in a laboratory.
R ed sp in el cr y sta ls
List five features of a mineral:
1.
2.
3.
4.
5.
8
Minerals are made of atoms, which are the basic structural
units of matter. They’re nature’s building blocks. Minerals
almost always form as crystals. A crystal is solid matter with
atoms arranged in a regular, repeating, three-dimensional
pattern. Mineralogists call this crystal structure.
A final feature all minerals share is a specific chemical
composition, which is sort of like a recipe. A mineral’s
chemical composition is its unique combination of atoms.
The recipe has to be perfect to grow a particular mineral.
For example, you can’t substitute salt in place of sugar in
a cookie and still get a cookie. The same holds true for
minerals.
Large mineral crystals grow when there’s just the right
heat, pressure, and time. Minerals can take on very beautiful
crystal forms. A mineral’s crystal form is an exterior
expression of its internal atomic structure. A crystal’s shape
is determined by the pattern the atoms follow. Crystals are
the raw material for most of the gems in jewelry.
atoms
combined atoms—the recipe for this mineral
crystal structure—a regular, repeating arrangement of atoms
crystal
9
D ia m on d
Some gems are harder than others. Some scratch easily. It’s
easier to scratch a fluorite than a diamond.
In 1822, a German professor and mineralogist named
Friedrich Mohs (MOZE) developed a system for rating the
relative hardness of minerals. Because diamond scratched
every other mineral, he gave it the number 10.
HARDER
Mohs Scale of
Hardness
The Mohs scale can be confusing. Without knowing anything
else about the minerals on the list, you might think that diamond is only a little harder than corundum. In fact, destructive scratch tests done with a diamond-tipped, weighted
lever show that diamond is 140 times harder than corundum and almost 124,000 times harder than talc.
Many everyday items measure about a 7 on the Mohs scale,
like a drinking glass for example. Any gem that has a lower
Mohs scale rating than topaz might pick up some scratches
from even the most careful wear. Even scratchy fabrics like
wool can, over time, strip away the lustrous outer layer of a
pearl.
SOFTER
C oru n d u m
T op a z
O r th o cla se feld sp a r
Q u a r tz
C a lcite
G y p su m
A p a tite
F lu o r ite
T a lc
10
10
9
8
7
6
5
MOHS RANKING
4
3
2
1
Mohs Scale of Hardness Worksheet
In boxes 1-3, circle whether the minerals in your canister are harder or softer than the tester mineral.
TESTER MINERAL:
#1
#2
softer or harder
#3
softer or harder
softer or harder
11
Gemology
Gemology is the study of gems.
A person who identifies and evaluates
gemstones is called a
T o p , d i a m o n d ; b o tto m , to p a z in a r a n ge o f co lo r s
12
What Is a Gem?
Almost all gems are minerals, but very few minerals qualify
as gems. To be a gem, a mineral must be beautiful, rare, and
durable. These three things make a gem desirable.
All gems should be beautiful. But because beauty is in the
eye of the beholder, people don’t always agree what’s
beautiful and what isn’t. Most people consider that beauty
is a combination of qualities that delight the senses or
appeal to the mind.
Rarity means there isn’t very much of something; it’s not
easily found. Some gems are rarer than others. A few, like
sphene or benitoite, are so rare they’re considered collectors’ items. Others, like amethyst or sapphire, are more
available.
To qualify as a gem, something must also be durable.
Durability is a combination of three factors: hardness,
toughness, and stability. Hardness measures how well a
gemstone resists scratching and abrasion. Toughness is a
gem’s ability to withstand breaking, chipping, and cracking.
Stability measures how well a gemstone resists the effects
of light, heat, and chemicals.
N eck la ce w ith sp essa r tite ga r n et a s a cen ter sto n e, gr een t sa v o r ite
ga r n et s, b lu e sa p p h ir es, a n d d i a m o n d s. N eck la ce a lso co n v er t s to
a b r o o ch .
List three features of a gem:
1.
2.
3.
13
Inclusions
What do inclusions tell us? They tell us whether a gemstone
grew in the earth, or in a laboratory. A tiny cluster of mineral
crystals in a ruby is nature’s signature. The gleam of a tiny
crystal in a gem is a window into the depths of the earth.
Inclusions are silent witnesses to the birth of gems. They tell
us how a gem formed, sometimes even where it grew.
Gems have many different kinds of inclusions. They can be
other minerals, gases, or liquids. In organic materials like
amber, inclusions can be things like leaves, bugs, or tree bark.
Inclusions serve as fingerprints for gemstones since no two
gems have the exact same inclusions. Because of the way
gems form, the chances of a truly inclusion-free gem are
extremely rare.
T op , in sect in clu sion in a m b er ;
b ottom , ga r n et in clu sion in d ia m on d .
14
T op , “lily p a d” in clu sion in p er id ot ; b ottom left,
h ea r t-sh a p ed i n clu si o n i n d i a m o n d ; b o t t o m
r igh t , b i r d -sh a p ed i n clu si o n i n d i a m o n d .
15
Phenomena
Some gems display special effects when they interact with
light. These stones are called phenomenal gems because they
display unusual optical effects.
Phenomenal gems like opal, moonstone, and fire agate get
their dazzling special effects from the way their structures
interact with light. Some can change color in different lighting
or reveal special effects when viewed in a certain direction.
T o p , sta r sa p p h ir e; b o tto m left , p la y -o f-co lo r in b la ck o p a l;
b o tto m r igh t , ca t’s ey e ch r y sob er yl w ith d i a m o n d s.
16
Looking at Phenomena Worksheet
Here’s a list of the different phenomena you might see in gems. Use a penlight to look at gems 1 through 6. Draw
the effect you see in each box. Write the name of each gem.
1. Asterism—Crossing bands of light, which create a star in
the dome of the cabochon.
2. Adularescence—A cloudy bluish white light, caused by
scattering of light.
3. Aventurescence—A glittery effect caused by light
reflecting from small, flat inclusions within a gemstone.
4. Chatoyancy—A band of light in certain gems, caused by
reflection of light from many parallel,
needle-like inclusions or hollow tubes (cat’s eye,
tiger’s eye).
5. Iridescence—A rainbow effect, similar to light reflected on
soap bubbles, created when light is broken up into spectral hues by thin layers.
6. Play-of-color—Flashing rainbow colors that sparkle as
light moves around the gem.
17
Tools of the Trade
Gemologists often use binocular microscopes to look at gems.
“Binocular” means you look with both eyes, which is more comfortable than looking through a single eye piece. Like a loupe, a
microscope can magnify an object 10 times its size. But unlike a
loupe, it goes up to 64X. That means your object will appear 64
times bigger! Microscopes can help you see things that aren’t
visible under 10X magnification. Microscopes have two types of
lighting: reflected lighting to examine the surface of stones and
darkfield lighting to examine the inside of stones.
18
A loupe is a handheld magnifier. It’s capable of making
an object appear 10 times larger than it actually is. 10X
is the standard magnification used throughout the gem
and jewelry industry to look at gemstones. Benefits of a
loupe are that it’s portable and easy to use once you get
the hang of it.
A darkfield loupe is a handheld magnifier with its own
light source. Darkfield illumination means that you’re
lighting the gemstone from the side against a built-in
black, non-reflective background. This helps you to see
inside the gem.
Tweezers are the instrument gemologists use to hold
stones. They help prevent the oils from your fingers from
getting on the gem. They’re also used for sorting large
quantities of small stones.
A stone cloth is used to remove debris and oils from
stones. It also keeps your stone in a safe place while
you’re examining it.
A penlight is a small handheld light source that is the size
of a pen. It supplies additional lighting and is used to
check for phenomena in gemstones.
F a cin g p a ge, a b o v e a n d b o tto m r igh t ,
G I A Ju n io r G em o lo gi st cla ss; to p r igh t ,
1 0 X d a r k field lo u p e a n d 1 0 X h a n d
lo u p es.
19
Gemstone Inclusion Activity
Overview
Examine gemstones and draw the gemstone inclusions you see.
Task
Examine the gemstone samples in your canister. First, examine the samples with your unaided eye. Then, examine the
gemstones with the required tools. Draw what you see inside the stone. Write “none” if you don’t see any inclusions.
20
Gemstone 1
Gemstone 2
Gemstone 3
Gemstone 4
Birthstones
and Lore
What’s your birthstone?
On the following pages you will find out the hardness
of your birthstone based on the Mohs scale, and which
powers your special stone has.
21
January—Garnet
Most garnets you see are dark red, but the most
valuable garnets are brilliant green or orange.
Hardness 7—71/2
Lore: Garnets are believed to have curative powers.
They cure depression, guard against injury, and protect
against poisons. They give the wearer loyalty and an
unchanging heart.
February—Amethyst
Amethyst is purple quartz. It is one of the most
popular stones used in jewelry. Hardness 7
Lore: Amethyst is said to control evil thoughts, quicken intellect, sharpen sense of sight, and protect wearer from
sorcery.
April—Diamond
The most common color of diamond is brown
to light yellow. Diamonds can be many different
colors as well as colorless. Hardness 10
Lore: Diamond symbolizes invincibility and gives its
wearer superior strength and good fortune.
May—Emerald
Emerald is the green version of beryl. Ancient
writings tell us that emeralds were found in
Cleopatra’s mines in Egypt. Hardness 71/2—8
Lore: Emerald is believed to heal the bites of venomous creatures and help memory. It endows its
wearer with the ability to see into the future.
June—Pearl
March—Aquamarine
Aquamarine’s name comes from “aqua,” which
means water and “marine,” which means sea. It is
the light blue version of beryl. Hardness 71/2 —8
Lore: Aquamarine is thought to cure pain in the throat,
stomach, liver, and jaw. It protects against perils at sea
and ensures safe voyages.
March—Bloodstone
Bloodstone is semitranslucent to opaque, dark green
with red to brownish red spots. Hardness 61/2—7
Lore: Bloodstone is believed to help stop blood flow
from wounds, give courage and wisdom to its wearers and
enable them to uncover enemy plots.
22
Pearls are translucent to opaque and virtually
any body color, but usually white or light yellow (called cream). Pearls come from oysters
and other mollusks. Pearls can be tiny or large,
round or irregular, and everything in between.
Hardness 21/2—4
Lore: Pearls are thought to cure ailments of the heart
and aid in peace of mind. They pull together one’s
mental and spiritual forces.
June—Moonstone
Moonstone is colorless to white, occasionally
green, orange, yellow to brown, or gray to
nearly black. Hardness 6—61/2
Lore: Moonstone is believed to bring good fortune,
cure epilepsy, encourage serenity, and even help
swimmers avoid accidents in the water.
June—Alexandrite
Alexandrite changes color under different
lighting. In daylight or fluorescent light it
looks yellowish, brownish, grayish or bluish
green; in incandescent light it looks orangy or
brownish red to purple red. Hardness 81/2
Lore: Alexandrite is thought to help cure spleen and
pancreas disorders. Alexandrite pulls sacred fires
together and stabilizes them.
August—Sardonyx
Sardonyx is semitransparent to opaque with
white or black bands alternating with reddish
brown bands. Hardness 61/2—7
Lore: Sardonyx is believed to protect its wearer from
bites of venomous snakes and gives one the power
of eloquence. It attracts quality friends and cures
insomnia.
September—Sapphire
July—Ruby
Ruby is the red variety of corundum. Large
transparent rubies are even rarer than diamonds. Hardness 9
Lore: Rubies are said to give courage and protect
against pain and poison. Rubies are believed to
preserve fruit on trees. They remove evil thoughts,
preserve mental health, and make the wearer
invincible to steel, swords, spears, and daggers.
(Don’t try this at home!)
August—Peridot
Peridot is found in volcanic flows and even in
meteorites from space called “pallasite.” It is
a yellowish green stone. Hardness 61/2—7
Lore: Peridot is thought to aid in digestion and ease
emotions. It purifies and balances physical being.
Sapphires come in nearly every color of the
rainbow except for red; red sapphires are
known as rubies. Hardness 9
Lore: Sapphires are thought to offer special healing
powers for profuse sweating, ulcers, eye trouble, and
hemophilia.
October—Opal
Opals come in virtually any body color,
displaying iridescent flashes called “play-ofcolor.” Opals are sensitive stones, and might
crack if they get too hot or too dry. Hardness 5—61/2
Lore: Opals are thought to provide the power of
prophecy and preserve golden color in blond women’s
hair. They empower its wearer with invisibility by
dimming the eyes of the beholder.
October—Tourmaline
Tourmaline is transparent to opaque and
comes in virtually all colors. Hardness 7—71/2
Lore: Tourmaline is said to protect against falls
on a journey and helps its wearer to be more objective. It also fosters inspiration and diminishes fears.
23
November—Topaz
Natural blue topaz is very uncommon in
nature. Most blue topaz has been treated with
radiation and then heated, which turns it blue.
Hardness 8
Lore: Topaz is believed to endow its wearers with
long life, beauty, intelligence, and sweet dreams.
November—Citrine
Citrine is transparent, yellow to orange to
brownish orange quartz. Hardness 7
Lore: Citrine is thought to dissipate negative energy,
purify body toxins, and cure liver and kidney
disorders.
December—Zircon
Zircon is transparent and can be colorless,
blue, yellow, green, brown, orange, red, and
occasionally purple. Hardness 6—71/2
Lore: Zircon is believed to dispel sadness,
insomnia, and increase the wearer’s riches, honor,
and wisdom.
24
December—Turquoise
Turquoise is semitranslucent to opaque, light
to medium blue, or greenish blue to green.
It’s most often mottled and might show dark
splotches or veins of matrix. Hardness 5—6
Lore: Turquoise is said to protect its wearer and the
wearer’s horse from injury. It counteracts spells and
aids one’s intuition.
December—Tanzanite
Tanzanite is transparent and can be blue to
violet to bluish purple. Hardness 6—7
Lore: Tanzanite is believed to have potent healing
abilities.
Word Search
ASTERISM
EROSION
LOUPE
PENLIGHT
SPECIES
CHATOYANCY
GEMSTONE
METAMORPHIC
ROCK
TWEEZERS
CRYSTAL
IGNEOUS
MINERAL
SEDIMENTARY
VOLCANIC
Answers on page 29
25
Crossword Puzzle
Across
2.
One of the December birthstones
3.
A birthstone thought to provide powers
of prophecy
5.
Unit of measurement for gem weight
8.
A tabletop magnifier
10. A gem’s ability to withstand wear,
heat, and chemicals
Down
1.
A person who studies mineralogy
4.
This organic gem is the birthstone for
June
6.
The basic unit of all matter
7.
Small, portable magnifying lens
9.
City where the GIA headquarters is
located
Answers on page 29
26
Glossary of Terms
Adularescence—The cloudy bluish white light in a moonstone, caused by scattering of light.
Gem species—A broad gem category based on chemical
composition and crystal structure.
Asterism—Crossing bands of light, which create a star in the
dome of a cabochon.
Gem variety—A subcategory of species, based on color,
transparency, or phenomenon.
Atom—The basic structural unit of all matter.
Gemologist—A person who studies gemology.
Aventurescence—A glittery effect caused by light reflecting
from small, flat inclusions within a gemstone.
Gemology—The study of gems.
Binocular microscope—A tabletop magnifier with two eyepieces.
Geology—The study of the earth.
Carat—Unit of measure for gemstones, equal to 0.2 gram or
200 milligrams, abbreviated “ct.”
Chatoyancy—A band of light in certain gems, caused by
reflection of light from many parallel, needle-like
inclusions or hollow tubes.
Chemical composition—Kinds and relative quantities of
atoms that make up a material.
Crystal structure—Regular, repeating internal arrangement of atoms in a material.
Geologist—A person who studies geology.
Group—A family of gems made up of several closely related
mineral species.
Hardness—How well a gemstone resists scratches and
abrasion.
Igneous—Rock formed by the crystallization of molten
magma.
Inclusion—A characteristic enclosed within a gemstone or
reaching its surface from the interior.
Inorganic—Composed of, or arising from, non-living matter.
Darkfield illumination—Lighting of a gemstone from the side
against a black, non-reflective background.
Iridescence—A rainbow effect created when light is
broken up into spectral hues by thin layers.
Durability—A combination of three factors: hardness,
toughness, and stability.
Karat—A unit of measure for the fineness of gold,
abbreviated “k” or “kt.”
Erosion—The transport of rock materials by natural forces.
Lore—Facts, traditions, or beliefs about gemstones.
Gem—A mineral that is beautiful, rare, and durable.
Loupe—A small, portable magnifying lens used for
examining gemstones.
continued on next page
27
Metamorphic—Rock altered by heat and/or
pressure, or by heated fluids from magma.
Toughness—A gem’s ability to withstand breaking,
chipping, and cracking.
Mineral—A natural, inorganic substance with a specific
chemical composition and a repeating crystal structure.
Tweezers—An instrument for holding gemstones.
Mineralogist—A person who studies mineralogy.
Weathering—Exposure to water, wind, and other
environmental conditions.
Mineralogy—The study of minerals.
Mohs scale—Used to rank the relative hardness of minerals
on a scale of one to ten.
Natural gems—Gems produced by natural processes,
without human help.
Organic—Produced by, or derived from, a living or
once living organism.
Penlight—A portable, handheld light source the size of
a pen.
Play-of-color—The flashing rainbow colors in opal.
Rock cycle—A constant formation and recycling process
that creates new rock from old.
Rock—A natural material made up of two or more minerals.
Sedimentary—Rock produced from the weathered and
eroded remains of existing rocks.
Stability—measures how well a gemstone resists the effects
of light, heat, and chemicals.
Stone cloth—Piece of fabric used for cleaning dirt and oil
from gems and holding them in place.
Synthetic—Manufactured in a labaratory.
28
PHOTO CREDITS
Joel Beeson, 8
BHP, 2
Valerie Power, 1 (bottom), 16 (bottom left)
Terri Weimer, 19 (top right)
Eric Welch, cover photo (right), Table of Contents,
2, 3 (left and right), 6, (right), 18, 19 (left)
Robert Weldon, 1 (top left and right), 12, 16 (bottom
right), 19 (bottom right)
ILLUSTRATION CREDITS
Judy Colbert, 21
Peter Johnston, cover (left), 5, 9, 10
Answers to Word Search
Answers to Crossword Puzzle
©2 0 1 1 T h e G em o lo gica l I n stitu te o f A m er ica
A ll r igh t s r eser v ed : P r o tected u n d er th e B er n e C o n v en tio n .
P r in ted in th e U n ited S ta tes.
29
GIA’s mission is to ensure the public trust in gems and jewelry by upholding the
highest standards of integrity, academics, science, and professionalism through
education, research, laboratory services, and instrument development.
GIA was established in 1931 by Robert M. Shipley. Mr. Shipley wanted to create an
institute that would serve the gem and jewelry industry by providing education to
jewelers.
The GIA Junior Gemologist Program is just one part of Robert Shipley’s legacy. To
learn more, we invite you to visit our website www.gia.edu
TM
GIA World Headquarters and
The Robert Mouawad Campus
5345 Armada Drive
Carlsbad, CA 92008
T 800 421 7250
T 760 603 4000, ext 4116
F 760 603 4199
E [email protected]
www.gia.edu