Diamonds & Gems
by
Barry Nicholls
Copyright 1997, 1999, 2000, 2001

(This is the text handout for the Adult Education class taught by Barry Nicholls at  nearby Barron Collier High School. Some of the illustrations are missing.)  Click here for info on next class
Paradise Jewelry Home Page

Table of Contents: (You can click on what you want to see)
4 C's 
   Color
   Clarity
   Cut
   Carat (Weight)
Gem Treatments and Enhancements
Weight Formulas
Mohs Hardness Scale
Gemstone Properties
Months of the Year Birthstones
Seasons of the Year Birthstones
Days of the Week Birthstones
Hours of the Day Birthstones
Zodiac Birthstones
Anniversary Gifts:
Care and Treatment of Gems (& Cleaning)
Choosing A Good Jeweler
Getting a Good Appraisal
Preventing Gem Switching
Opal Grading 
Pearl Grading
Crystals & Healing
Suggested Reading

Diamonds & Gems

What is a gem?  A gem is something which has Beauty, Durability, Rarity, and Value.

A butterfly's wing has beauty, rarity, and value, but no durability. A fine Opal may have the same colors and beauty. It has rarity and value and is relatively durable (if not abused), so it is considered a gem.

Gems can be classified as Organic and Inorganic. Most gemstones are inorganic. Rubies, Sapphires, Topazes, etc., form as crystals of minerals and are inorganic. Some "gem materials", however, are formed organically. Pearls, Coral, Amber, Jet, Ivory, and Shell, are all organic gem materials. We also have some gem materials that were organic, but come to us as mineralized fossils. Ammolite, and Opalized bone are examples of this.

It is important to know the difference between Natural, Treated, Synthetic, and Imitation.

Natural gems have formed without any help from Man. They may then be treated or untreated. Many natural stones are treated in some way to bring out beauty that nature didn't. Almost all Citrine on the market today was mined as Amethyst and later heated to change it's color from purple to yellow. Blue Topaz is very rare in nature, but colorless topaz can be irradiated and heated to give it the lovely blue color we're accustomed to seeing in jewelry. We will cover more on treatments later.

Synthetic stones have all the physical, chemical and optical properties of a natural stone, but they have been created by Man. Some people use natural Sapphire, grind it up and grow new crystals (recrystallize it). They may be tempted to call the resulting stones "natural", but whether the material came from nature or from a laboratory supply house, the resulting stone is man-made and therefore "synthetic".

Imitation stones do not have the same properties as the stone they are imitating. They just have the appearance. Rhinestones are made of glass and have none of the distinguishing properties of a Diamond, but they look like fine Diamonds.

You have probably heard gemstones referred to as "precious" and "semi-precious". We no longer use those terms because they can be misleading. A very fine Jade may be worth many thousands of dollars. Many Black Opals cost between $1000 to $5000 per carat. A fine red Topaz of several carats may cost $10,000. "Precious" stones (the big four) may cost only a few dollars per carat. Poor quality Diamonds can be bought for a few hundred dollars per carat and Rubies, Sapphires and Emeralds may go for as little as two or three dollars per carat.....hardly what we would call "precious".

4 C's        $25 Million Diamond Inventory (searchable!)

When judging the value of a stone you will need to judge the famous "4 C's". They are Color, Clarity, Cut, and Carat (weight). The 4 C's are basically a way of quantifying BEAUTY. Durability and rarity are also important, but all things being equal, beauty will make the difference between high and low value in a gem.

If you compare two Sapphires side by side and they are alike in all but color, the more beautiful color will cost more. If you compare two Topazes side by side, the more intense color will be more valuable.

People often ask: "Is the darker color more valuable than the lighter color?" Here the proper way to find the answer is to consider beauty. A stone that is too light will not be very attractive. A stone that is too dark will be dull and lifeless. The stone with an intense color and lots of flashes of light will be eye catching and very attractive. That is the stone to look for.

Back to the 4 C's. If you have two stones of very lovely intense color, the stone with the most clarity will be the most beautiful.

Between two stones with fantastic color and flawless clarity, the better cut of the two will show itself to best advantage. A poorly cut flawless diamond will look like a piece of cheap glass. Proper cutting makes the best use of the optical properties of a stone. That is where the sparkle and brilliance come from.

Finally, all things being equal, the larger stone will be worth more. Some stones such as Amethyst and Citrine are easy to find in large sizes so their "per carat" price changes very little with size. Many stones, however, are rare in larger sizes and the per carat price skyrockets in larger stones. Alexandrite is a good example. Small gems of under a carat can be expensive, but when they get over a carat the price jumps even higher.

Keep in mind that stones form in nature, kind of like in your backyard in the dirt. Nature isn't exactly a cleanly swept laboratory so gems usually have various imperfections or "inclusions" in them. When a gem crystal is found, it may be easy to find a small area of perfection in it to cut into a small gem. A large piece of perfection is much more rare and so will be much more valuable.

COLOR

We will begin by discussing color in Diamonds. Diamonds come in all colors. The most expensive stones in the world are red Diamonds. A 1 carat red Diamond sold at auction for approximately one million dollars!

Diamonds are usually thought of as being white, and the less valuable ones as off-white. When a Diamond has enough color to be a "colored" Diamond it is known as a "fancy".

First we'll talk about white and off-white Diamonds. The Gemological Institute of America has the most widely accepted grading system for Diamonds. When they invented their system they decided that since A, B, and C, had already been widely used (and misused) for many things they would avoid those letters and start with D.

Thus it is that a completely colorless (white) Diamond is graded as a "D". Loose Diamonds up to G will usually appear colorless. When they are set in yellow gold you won't be able to judge color. A stone with an easily distinguished yellow tinge will be completely masked by yellow gold.

D, E, and F stones are considered colorless. G, H, and I are excellent and it really takes an expert to notice that they have any color to them. J, K, and L are noticeable but accepted by most people. M through Z are obvious. After Z begin the "fancy" yellow Diamonds, etc. From D to Z the value goes down. After Z the value may go up again. That depends on several factors. Rarity is one important factor.

Red is the rarest color of Diamond. It is also attractive, so it's the most valuable. Pink is next in line; it's really just a light red. Blues, greens and yellows are very pretty in the strong tones. An important thing to mention here is the fact that Diamonds can be irradiated to achieve color. Very often, off color Diamonds are subjected to either neutron or electron bombardment to give them a fancy color. Irradiated Diamonds are usually a brighter and stronger color than natural fancies. The process is permanent and beautiful but irradiated Diamonds are much less expensive.

You have probably heard the term "blue-white" used in describing Diamonds. True blue-white Diamonds are very rare, and the term is no longer used by good jewelers. A blue white Diamond is one that is very white (D color) but in ultraviolet light (such as sunlight contains) it has a slight bluish fluorescence. The term became very much abused some years ago by unscrupulous dealers. Some dealers were even calling K and L color stones blue-whites!

Gems other than Diamonds are usually referred to as "colored stones". Many types of stones that we are used to thinking of as being a particular color, actually come in many colors. Diamonds and Sapphires come in all colors. Sapphires (the mineral corundum) are called Rubies when they are red. Garnets are commonly red and brownish red, but they also come in orange, pink, purple, and green. Fine green Garnets rival fine Emeralds and are much more durable.

Topazes are well known in the yellow color known as "Precious" Topaz, but they also come in champagne, sherry, blue (from very light to quite dark), pink (known as imperial Topaz), and all the way to cherry red (rare and very expensive). Citrine and Amethyst are two different colors of Quartz, which also comes in light to dark smokey color, often mistakenly called Smokey Topaz. The mineral Beryl comes in several colors. Green Beryl with the impurity chromium is called Emerald. With iron as a color causing impurity it will be blue and is called Aquamarine. Pink is called Morganite, yellow is called Heliodor, and colorless is called Goshenite. Spinel, Zircon, and Tourmaline all come in many colors too.

CLARITY

The next of the four C's is clarity. It is normal for stones to have small inclusions in them. Less inclusions mean more value. The GIA definition of an internally flawless Diamond is one in which "an expert, with a ten power magnification, can not find any inclusions". Inevitably that same stone may show many inclusions if the magnification is stepped up enough.

Between two equal stones, the one with less inclusions will be more attractive....that is where the value lies.

Most faceted stones are cut so that light will enter, reflect, and come back out toward the eye, thus giving flash and brilliance. Any inclusions in the stone will block that light and prevent it from coming back out. Too many inclusions will make a stone cloudy or dead looking. In Emeralds inclusions are so frequent that they have been given the name "garden" and they are viewed as normal. Flawless Emeralds are available but they are more rare than other flawless stones and correspondingly more expensive.

There are many kinds of inclusions. In Diamonds, dark inclusions are usually called "carbon" spots, but actually the only part that is not carbon is the inclusion. The diamond is made of carbon and the inclusion is a foreign particle contained in it. Garnet, Peridot, Pyrite, Hematite, and Spinel are frequently found in diamonds. The inclusion may look black, but it rarely is actually black and it's not carbon. There are also white inclusions and they are usually harder to spot. Being hard to see, they don't detract from the stones value as much as an obvious dark inclusion.

When looking for inclusions in a stone, with or without magnification, turn it in various directions and rock it slowly back and forth, looking for any specks or spots, lines or "feathers" inside the stone. Don't let dirt or lint on the surface fool you. It's important to get the stone as clean as possible or you are wasting your time. Whenever possible, look at the stone from the bottom or "pavilion". Especially in the case of Diamonds, it is much easier to see inclusions from the bottom. A well cut Diamond is reflecting a lot of light out the front and looking for inclusions is a little bit like trying to read the writing on a car headlight from the front while it's on.

Here is an approximation of the Gemological Institute of America clarity grading criteria:

Using ten power magnification the inclusions seen are:

MINUTE                 "extremely difficult to see"             VVS1

                                  "very difficult to see"                     VVS2

MINOR                     "difficult to see"                             VS1

                                    "somewhat easy to see"                 VS2

NOTICEABLE           "easy to see"                                SI1

                                    " very easy to see"                         SI2

OBVIOUS                  "Beauty or Durability somewhat      I1
                                    affected"

                                    "Beauty or Durability seriously         I2
                                    affected"

PROMINENT             "Beauty and Durability seriously     I3
                                        affected"

Our third C is cut. We are going to deal with faceted stones, that is, stones cut with flat faces or facets. If a stone is cut properly, light will enter it, reflect or bounce around, and come back out to be seen and enjoyed. You may notice that if you hold a piece of glass and tilt it, at a certain point you can't see through it any more. You begin to see a reflection. Inside a gemstone, the angle has to be right for that light to reflect also. If the stone is not cut properly, light will pass through instead of reflecting back. That results in a transparent, washed out looking stone. We call that "windowing".

In stones with high refractive indices, light is split into it separate colors, like in a prism. That is why a Diamond sparkles with all the colors of a rainbow. Again the stone must be cut properly to take advantage of it's light splitting properties.

When trying to judge a stone, you will get a big clue about it's quality from how well it is cut. High quality material is usually given the respect of good cutting. Poor material is not usually considered worth the time, trouble, and extra expense of careful cutting. Synthetics may be exceptions to this because they are cheap and are often cut on machines without worrying about loss of weight in cutting.

When viewing a round Diamond, the symmetry of the cut is a big clue to its quality. the table (the flat top of the stone) should be exactly the shape of a stop sign. If it is lopsided or uneven, it is not well cut, and may not be a very good stone. Small parallel grooves on the facets come from polishing the stone in too much of a hurry and are called "fast polish checks". Another big clue. If you hold the stone in such a way as to see light reflected off of the facet, you can usually see its symmetry and polish even without magnification.

Look at the overall symmetry of the stone. Is a round stone actually round or a little out of round? Is a square stone even on all sides? Are the sides parallel? Is the table centered at the top?

The main cuts you will see are Round, Oval, Emerald cut, Marquise or Navette, Pear shape or Teardrop, and Baguette (straight and tapered).

Different cuts have different values, varying with the type of stone. Marquise cut Diamonds are the most expensive for two reasons. There is a great demand for that cut and the weight lost in cutting is greater than in other cuts. The least expensive cut in large Sapphires is the oval cut. A three carat round Sapphire is very hard to find but a three carat oval is not.

ROUND BRILLIANT	SINGLE CUT	ANTIQUE CUSHION CUT
MARQUISE	PEAR OR TEARDROP (PENDELOQUE)	OVAL
EMERALD CUT (OCTAGON)	BAGUETTE	TAPERED BAGUETTE
PRINCESS CUT	RADIANT CUT	SQUARE CUT
TRIANGLE	TRIELLE	TRILLIANT

OLD MINE CUT

Some other cut names and variations:

CABOCHON CUTS are rounded, most often have flat bottoms and don't have facets. Opals, and Tigereyes are usually cut cabochon style. Cabochons are also cut in the same basic shapes and would be called: round cabochon, square cabochon, oval cabochon, etc.

CARAT (Weight)

The last of our Four C's is carat weight. One carat consists of 100 points just as there are 100 cents in a dollar. That means that a 25 point stone will be a quarter carat, a 66 point stone will be two thirds of a carat, etc. 5 carats equal one gram, so a one carat stone weighs one fifth of a gram (.20 grams). Don't get confused between Karat and Carat. Karat refers to the purity of gold and we will cover that later.

Carat weight affects the value of a stone in three ways. First, obviously a two carat stone (all things being equal) will cost more than a one carat stone simply because there is twice as much of it. Second, when cutting the rough stone, it will always be easier to find a small piece of relative perfection than a large piece. Third, some stones are rarely found in sizes over a few carats, so, while small ones may not be too expensive, slightly larger ones may suddenly be very expensive.

Citrine, Amethyst, Smokey Quartz, and Blue Topaz are frequently found as very large stones and the per carat price is usually the same even in the larger sizes. The same quality of peridot may be $10 to $15 per carat in a small size and $60 to $100 per carat in a three or four carat size.

WEIGHT FORMULAS

We will examine some very useful formulas for estimating the weights of Diamonds. You may want to use these if you'd like to estimate the weight of a mounted stone or maybe a loose stone if you don't have a scale.

Estimated weight = average diameter squared x depth x .0061

Estimated weight = average diameter squared x depth x .0062

EMERALD CUT

Estimated weight = length x width x depth x adjustment factor

Length-to-width ratio Adjustment factor

1.00:1.00         0.0080
1.50:1.00         0.0092
2.00:1.00         0.0100
2.50:1.00         0.0106

Length-to-width ratio = length divided by width

Estimated weight = length x width x depth x adjustment factor

Length-to-width ratio Adjustment factor

1.50:1.00         0.00565
2.00:1.00         0.00580
2.50:1.00         0.00585
3.00:1.00         0.00595

Length-to-width ratio = length divided by width

Estimated weight = length x width x depth x adjustment factor

Length-to-width ratio Adjustment factor

1.25:1.00         0.00615
1.50:1.00         0.00600
1.66:1.00         0.00590
2.00:1.00         0.00575

Length-to-width ratio = length divided by width

Diamond Diameters and Corresponding Weights (These are approximate)

1.15mm               .005ct
1.35                     .01
1.55                     .02
1.90                     .03
2.10                     .04
2.30                     .05
2.70                     .06
2.90                     .07
3.10                     .10
3.50                     .15
4.10                     .23
4.50                     .33
5.13                     .50
5.88                     .75
6.50                     1.00
6.90                     1.25
7.40                     1.50
8.20                     2.00

Most of the gems that you see on the market today have been treated or enhanced in some way. Some people are disappointed to learn this. The positive side is that because of these treatments and enhancements, you can own and enjoy a fine gem without having to be extremely wealthy or the equivalent of royalty.

Here's a list of Treatments:

Heat
Radiation
Drilling (and Lasering)
Oiling
Sealing
Dyeing
Bleaching
Painting or Coating
Foilbacking
Fracture Filling

White Topaz is irradiated and then heated to create Blue Topaz. Diamonds can have dark inclusions removed by laser drilling. A very thin hole is drilled down to the inclusion and acid is introduced to dissolve it. Now the same "inclusion" is there but it is now a clear vacant space instead of a dark (and easily seen) spot. The Diamond is now a bit more attractive and thus easier to sell. Emeralds have been oiled since ancient times. Different kinds of oils that have the same or almost the same refractive index are used to fill cracks and fractures. The result is that the cracks are now invisible, thus making for a much more attractive gem. If colored oils are used then it is also dyeing. Many gems can be dyed as long as they are either porous or cracked. Pearls are often bleached. Coral is too. The backs of gems can be painted to make them seem to be of strong, more intense color than they really are. Foilbacking is the mirror backing that makes rhinestones so brilliant. Fracture filling (also called the Yehuda process or clarity enhancement) makes cracks and fractures invisible like in oiling except that the process is more durable. This is used in Diamonds and is becoming common in Emeralds too. In Diamonds the fracture fillers use very high heat and pressure to force a special glass-like filler into the cracks that reach the surface. In Emeralds a two part clear epoxy called Opticon can be used.

Gem treatments are wonderful when they are used to enhance the beauty of a gem. FULL DISCLOSURE is the LAW. These treatments can also be misused to sell less expensive gems as their more expensive cousins. Make sure you go to a jeweler or gem dealer who keeps up with new developments and can tell the difference.

MISNOMERS

There are a number of incorrect names for gems and they can be confusing and misleading. Here are a few of the more common ones, and the actual stone referred to:

Arkansas Diamond                             Quartz crystal
Herkimer Diamond                             Quartz crystal
Balas Ruby                                         Garnet
Colorado Ruby                                    Garnet
Montana Ruby                                     Garnet
Cape Ruby                                          Garnet
Water Sapphire                                     Iolite
Poor Man’s Tanzanite                            Iolite
Smoky Topaz                                        Smoky Quartz
Indian Jade                                           Aventurine
Manchurian Jade                                   Soapstone
Nassau Pearl                                         Conch Pearl

Hardness

An important property of gemstones is their hardness. Diamond is the hardest and is rated a hardness of ten on the "Mohs" scale. A man named Mohs rated different gem materials according to their hardness relative to one another. It's important to remember that hardness and toughness are not the same. Diamond is the hardest, but Jade is the toughest!

Hardness is the measure of how easily something can be scratched and on the Mohs scale any material with a lower number can be scratched by any material with a higher number.

Here are the results of Mohs original research:

1 Talc                         6 Feldspar
2 Gypsum                   7 Quartz
3 Calcite                     8 Topaz
4 Fluorspar                 9 Corundum (Sapphire & Ruby)
5 Apatite                     10 Diamond

This scale is not linear. As it happens, Diamond is actually about 20 times as hard as Sapphire. A fingernail is about 2.5 and a steel file is about 6. Glass is 5 so not only will a Diamond scratch glass, so will most things. Opal at 5.5 to 6.5 will scratch glass and of course C.Z. (Cubic Zirconia) at 8 to 8.5 will scratch it too!

Diamond                     10                         2.417                                 3.52  +-.03
Cubic Zirconia             8.5                        2.15                                   5.80  +-.20
Corundum                     9                         1.762 to 1.770                    4.00  +-.03
Chrysoberyl                 8.5                        1.746 to 1.755                    3.73  +-.02
Beryl                            7.5-8                    1.577 to 1.583                    2.67-2.84
Garnet                         6.5-7.5                  1.72 to 1.875                      3.30-4.18
Opal                             5.5-6.5                 1.45                                    1.25-2.22
Ammolite                                                   1.52 to 1.67                        2.8
Peridot                          6.5-7                    1.654 to 1.690                    3.31-3.48
Quartz                           7                          1.544 to 1.553                     2.66  +-.01
Spinel                             8                         1.718                                   3.57-3.90
Topaz                             8                         1.619 to 1.627                     3.53  +-.04
Tourmaline                     7-7.5                   1.624 to 1.644                     3.01-3.21
Zircon                            6-6.5                   1.810 to 1.984                     3.93-4.73

We are all familiar with the idea that there are birthstones corresponding to the months of the year. There are also birthstones for the days of the week, the seasons, the hours of the day, and the signs of the Zodiac.

Here are the commonly accepted birthstones:

MONTHS OF THE YEAR                                            Loose Gemstones

January             Garnet                                                          Garnet Jewelry   
February          Amethyst                                                       Amethyst Jewelry
March              Aquamarine, Blue Topaz, Bloodstone            Blue Topaz & Aquamarine Jewelry
April                 Diamond                                                       Diamond Jewelry
May                 Emerald                                                         Emerald Jewelry
June                 Alexandrite, Pearl, Moonstone                        Pearl Jewelry
July                  Ruby                                                              Ruby Jewelry   
August             Peridot, Sardonyx                                           Peridot Jewelry
September       Sapphire                                                         Sapphire Jewelry
October           Opal, Rose Quartz, Tourmaline                       Opal Jewelry    Tourmaline Jewelry   About Opals, Octobers Birth Stone
November        Topaz, Citrine
December         Blue Topaz, Blue Tourmaline, Blue Zircon,
                        Turquoise, Lapis Lazuli, and Tanzanite         Loose Blue Topaz   Blue Topaz Jewelry   
                                                                                           Blue Tourmaline Jewelry  Tanzanite Jewelry

Spring               Emerald
Summer             Ruby
Fall                    Sapphire
Winter               Diamond

Sunday             Topaz
Monday            Pearl, Crystal Quartz
Tuesday            Ruby, Emerald
Wednesday       Amethyst, Lodestone
Thursday           Sapphire, Carnelian
Friday               Emerald, Cats-eye Chrysoberyl
Saturday            Diamond, Turquoise

HOURS OF THE DAY

1 A.M.         Smoky Quartz         1 P.M.         Zircon
2                 Hematite                    2                 Emerald
3                 Malachite                   3                 Beryl
4                 Lapis Lazuli                4                 Topaz
5                 Turquoise                   5                 Ruby
6                 Tourmaline                 6                 Opal
7                 Chrysolite                   7                 Sardonyx
8                 Amethyst                    8                 Chalcedony
9                 Kunzite                       9                 Jade
10                Sapphire                   10                Jasper
11                Garnet                      11                Lodestone
12                 Diamond                  12               Onyx

Aquarius (Jan. 21 - Feb. 21)             Garnet
Pisces (Feb. 21 - Mar. 21)                Amethyst
Aries (Mar. 21 - Apr. 20)                 Bloodstone
Taurus (Apr. 20 - May 21)                Sapphire
Gemini (May 21 - Jun. 21)                 Agate
Cancer (Jun. 21 - Jul. 22)                  Emerald
Leo (Jul. 22 - Aug. 22)                     Onyx
Virgo (Aug. 22 - Sep. 22)                 Carnelian
Libra (Sep. 22 - Oct. 23)                   Chrysolite
Scorpio (Oct. 23 - Nov. 21)               Beryl
Sagittarius (Nov. 21 - Dec. 21)           Topaz
Capricorn (Dec. 21 - Jan. 21)             Ruby

So, as you can see, you have many choices if you ever want to buy or wear your birthstone. If you don't like "your" birthstone, you can probably find another one that you do like!

While we're on the subject of appropriate stones, here's a list of appropriate Anniversary Gifts:

Year 1-11         Remembrance
12                     Agate
13                     Moonstone
14                     Moss Agate, Ivory
15                     Crystal Quartz
16                     Topaz
17                     Amethyst
18                     Garnet
19                     Hyacinth
20                     China
25                     Silver
30                     Pearl
35                     Coral, Jade
40                     Ruby
50                     Gold
55                     Emerald
60                     Diamond

Some gems are very durable and hardy; they will take a lot of abuse without much damage. Others are easily chipped, broken, scratched, or otherwise damaged.

To be on the safe side, all gems and jewelry should be treated with care and respect.

To be on the safe side, let's start with some of the delicate stones.

Stones to be careful of are: Amber, Coral, Ivory, Emerald, Kunzite, Lapis Lazuli, Opal (especially doublets and triplets), Pearls, Peridot, Shell Cameos, Tanzanite, Topaz, Turquoise, and Zircon. (Zircon is not Cubic Zirconia.)

Strong cleaning solutions and heat may have a negative effect on some stones or on their enhancements. Emeralds or Rubies that have been oiled may lose their oil. Waxed or dyed Turquoise may lose it's wax or dye and become colorless or chalky. Doublet or triplet Opals may come apart. Pearls may lose their luster.

If a stones enhancement is wiped out, it can often be put back. Oiled stones can be re-oiled. Dyed stones can be re-dyed. Chipped or cracked stones, however, can only be recut, and pearls are gone forever.

Pearls are delicate and should only be put on after all make up, perfume, and hair spray have been applied. Keep them away from any chemicals. If they are worn against the skin, they should be wiped carefully with a soft, damp cloth after each use. If worn more or less frequently, they should be restrung once or twice a year. If you see the string between the pearls becoming dark or stained, get them restrung immediately. That soiling may get into the pearls and become permanent.

Avoid temperature extremes, or rapid temperature changes with most gemstones. Opals, for example, contain as much as 11 percent water, and freezing or boiling may destroy them!

There are many cleaning solutions available commercially, but if you want to use something else, you can use detergent ammonia from under your kitchen sink. Dip a toothbrush in the ammonia and scrub your jewelry with it, then rinse it well. Do NOT soak your jewelry in bleach or ammonia! For your diamond and gold pieces, you can then boil them to get at any dirt that your toothbrush was unable to reach. Diamonds and gold can withstand a lot of heat, and boiling water can only reach 212 degrees Fahrenheit, so those pieces will be safe. Don’t do this with anything but Diamonds and gold! Use a few drops of liquid dish detergent in the water to cut grease and oil. Don't use too much or the pot will boil over and make a mess on your stove, and don't forget and let the pot boil dry, you will ruin your pot and possibly your jewelry too.

Here is a list of stones and their usual reactions, with the following abbreviations:

Hardness H                                 Toughness T
Reaction to boiling RB                 Reaction to ultrasonic RU
Reaction to steaming RS               Reaction to acid RA

Alexandrite         8.5     v.good           good         good         good         good
Amber                 2         poor            poor         poor          poor         poor
Amethyst             7         good             fair          fair             good         fair
Andalusite         7.5         good             fair         fair             good         fair
Aquamarine         8         fair                 fair         fair             fair           good
Citrine                 7         good              fair         fair             good         fair
Coral                 3.5         poor             poor       fair             fair            poor
Cubic Zirconia     8.5       good             good      good         good          good
Emerald             7.5         poor             poor       poor          fair             poor
Diamond             10         good            excl        excl           excl            excl
Garnet                 7          fair                poor      fair           good           poor
Hematite             6          fair                 good      good         good          poor
Ivory                 2.5         fair                 poor     good         fair             fair
Jadeite               6.5         excl               good     good         good          poor
Kunzite             6.5         v.poor            poor     poor         fair              fair
Lapis Lazuli       5.5         poor              poor     good         fair             poor
Moonstone         6.5         poor             poor     fair            fair             poor
Nephrite             6.5         excl             good     good         good           poor
Opal                     6         v.poor          poor     poor          poor             poor
Pearl                     3         poor             poor     fair            fair             v.poor
Peridot                 6.5       poor             poor     poor         fair             poor
Ruby                     9         v.good         good     good         good         good
Sapphire                9         v.good         good     good         good         good
Shell cameo         3.5         poor             poor     poor         fair            v.poor
Spinel                     8         fair                fair       good         good         good
Tanzanite               6.5       poor             poor     poor         poor         fair
Topaz                     8         poor             poor     poor         fair           good
Turquoise             5.5         poor             poor     fair           poor         v.poor
Tourmaline             7.5         fair             fair         fair           good         fair
Zircon                     6.5         poor          poor       poor         fair           fair

Due to lack of space I didn't put ranges of hardness for the stones having some variations in their hardness. For a more accurate listing of stone hardnesses, see the Gemstone Properties Table on page 13.

If you are new in town and looking for a good jeweler, here are a few tips:

Check with the Better Business Bureau and the Chamber of Commerce. Being a member is no guarantee that they are good, just as not being a member is not necessarily an indication that they are not good. You’re just looking for an overall pattern that will help you choose.

                    Ask around. Who do your new friends recommend and why?

Start small. Take in a small repair and see how they treat you. Watch how they treat other people too.

Ask a few questions about gems and jewelry. Do they take the time to share their knowledge (Assuming they’re not swamped at the time)?

                    Are they members of any professional organizations of jewelers?

                    What education do they have in jewelry and gemology?

                    Do they continue their education with new courses and refresher courses?

Do they have (and know how to use) any jewelry/gemological equipment? (Microscope, Diamond tester, Moissanite tester, gold tester, etc.)

Some key elements to a good appraisal are:

Name and Definition of the appraisal. There are many different kinds of appraisals with different legal definitions and different purposes. The name of the type of appraisal and its definition should be on it.

                    Name, qualifications, and affiliation of the appraiser.

                    Definition of terms and grades.

Description of the item. An accurate, detailed description is crucial.  A good photograph and grading and plotting of any major diamonds is a must.  The most common form of appraisal is an insurance appraisal whose purpose it is to make you whole in the case of loss or damage to your piece. You can’t be made whole unless you know exactly what you had.  

                    Value. (This is usually only there to set your premiums if it is an insurance appraisal)

A good description will include the following:

                    Style
                    Weight
                    Measurements (finger size, length, width, thickness, etc.)
                    Number and kind of stones.
                    Measurements and weights (often by approximation) of stones.
                    Type of construction (cast, hand fabricated, etc.)
                    Distinctive stamps or markings

Appraisal Organizations (These are organizations that require ongoing training in appraisals sciences):

                    National Association of Jewelry Appraisers
                    International Society of Appraisers

Preventing Gem Switching

There are several ways. First, identify your stone. You can get it appraised and have a "plot" or map done of your stone. This will show any characteristic inclusions that make your gem easy to identify. You can also have a picture taken called a "gem print" that maps the unique cutting and light reflecting characteristics of your gem. You can have an identifying number laser inscribed on the girdle (circumference) of your gem. When leaving your jewelry with anyone, make sure that they know the gem is identified. Then there is no incentive to switch as it would be easy to prove.

Opal Grading         Opal Lore        Opal Jewelry

The factors to consider in grading opals are:  Size of Colors, Number of Colors, Brightness/Life, Inclusions, Size, and Cut.

An opal with large patches of color is worth more than an opal with small patches of color.  Several colors are worth more than one color.  The brightness of the colors is very important.  Bright, vivid colors are more valuable than muted, dull colors.  Look for extinction.  That is what happens when you turn an opal different ways and the colors can only be seen in some directions and not others.  The more life and less extinction an opal has, the more valuable it is.

Inclusions (unless they are interesting, such as one that is in the shape of Australia or something) detract from the value.

A large opal (all things being equal) is worth more than a small one up to a point.  If an opal is too large to be useful for anything, it is hard to sell, and thus less valuable.

A well cut opal will be symmetrical, well polished, and not lumpy. 

Many opals that used to be bright and lively, seem to lose their color.  People say that they "dried out" and that's why they lost their color.  Take a closer look.  Is the surface "frosty" looking?  Opals are not hard to scratch and frequent wearing will put a lot of tiny scratches on the surface.  Then it is like trying to see a rainbow through frosted glass.  The colors are there, but very dull.  Polishing the opal will bring the colors back to their vivid best.

Pearl Grading                Pearl Lore       Pearl Jewelry

Cultured pearls are the result of inserting a bead nucleus into a pearl oyster and letting it coat that nucleus with NACRE.  Beads are cut from Mississippi River clams and sent to Japan where they are used to culture Akoya (salt water) pearls.

Pearls are graded on a number of factors similar to diamond grading.  The 4 C's of pearls would be Lustre and Orient (color), blemishes (clarity), shape (cut), and size (carat weight).

Lustre and Orient are the result of the thickness of the Nacre.  Nacre is the coating that the oyster deposits over the bead nucleus inserted by the oyster farmer.  The thicker it is, the more of a "sheen" the pearl will have.  There is a brightness and surface play of color somewhat like the sheen of an oil slick.  The finer the pearl the sharper a reflection will be on its surface.  A poor pearl will be dull and show little or no reflection.  On a very fine pearl, you may be able to see yourself clearly.  Pearls come in all colors.

It is normal to have some blemishes on the surface of the pearl.  More blemishes mean less cost.  Evenness of color is also important.

Pearls come in a variety of shapes.  Freshwater or Biwa pearls look like Rice Krispies although now the Chinese have developed round freshwater pearls.  "Round" pearls are classified as round, semi-round, and baroque.  

It is hard to find perfectly round pearls.   Matching size and color is also time consuming so a well matched strand can be costly.

Here are a few beliefs about what healing powers area associated with certain crystals.
Amethyst: Acne, adenoids, alcoholism (and/or getting drunk), cankers, eczema and gum ailments.
Azurite: Asthma (and other respiratory ailments) and tonsillitis.
Cerussite: Abscesses, conjunctivitis & other eye ailments, headaches, emotional stress, and hyperactivity.
Cinnabar: Bladder ailments, back pain, appendicitis, leg circulation and hemorrhoids. (WARNING! Cinnabar contains mercury! I don’t recommend handling it and especially don’t heat it, boil it or eat or drink anything that has come in contact with it!)
Malachite: Bronchitis, diabetes, heart ailments, flu and pleurisy.
Pyrite: Circulatory problems, liver and kidney aliments, dry skin, gastritis, and flatulence.

Australian Aborigines, among other indigenous populations, also still use Crystals for medicine. Their favorites are Multi-Color Crystals, as they believe that they hold the energy of the Rainbow Serpent, acting as a bridge between the spirit and physical worlds.

Suggested Reading:
Gems and Jewelry - Joel Arem
Gemstones of the World - Walter Schumann
Jewelry & Gems, The Buying Guide - Antoinette Matlins

Education:
Gemological Institute of America (GIA): 1 (800) 421-7250
Gemological Institute of America (GIA Online)
Texas Institute of Jewelry Technology 1(800) 232-5804 Paris Jr. College
How To Buy A Diamond - by GIA  A Four C's Primer

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