 Natural gemstones are found in nature. Laboratory-created stones,
as the name implies, are made in a laboratory. These stones, which
also are referred to as laboratory-grown, manufacturer-created, or
synthetic, have essentially the same chemical, physical and visual
properties as natural gemstones. Laboratory- created stones do not
have the rarity of naturally colored stones and they are less expensive
than naturally mined stones. By contrast, imitation stones look like
natural stones in appearance only, and may be glass, plastic, or less
costly stones. Laboratory-created and imitation stones should be clearly
identified as such.
Gemstones may be measured by weight, size, or both. The basic unit
for weighing gemstones is the carat, which is equal to one-fifth (1/5th)
of a gram. Carats are divided into 100 units, called points. For example,
a half-carat gemstone would weigh .50 carats or 50 points. When gemstones
are measured by dimensions, the size is expressed in millimeters (for
example, 7x5 millimeters).
Gemstone treatments or enhancements refer to the way some gems are
treated to improve their appearance or durability, or even change their
color. Many gemstones are treated in some way. The effects of some
treatments may lessen or change over time and some treated stones may
require special care. Some enhancements also affect the value of a
stone, when measured against a comparable untreated stone.
A WORD ABOUT PEARLS.
 Natural or real pearls are made by oysters and other mollusks. Cultured
pearls also are grown by mollusks, but with human intervention; that
is, an irritant introduced into the shells causes a pearl to grow.
Imitation pearls are man-made with glass, plastic, or organic materials.
Because natural pearls are very rare, most pearls used in jewelry
are either cultured or imitation pearls. Cultured pearls, because they
are made by oysters or mollusks, usually are more expensive than imitation
pearls. A cultured pearl's value is largely based on its size, usually
stated in millimeters, and the quality of its nacre coating, which
gives it luster.
ALL THAT GLITTERS
 The word gold, used by itself, means all gold or 24 karat (24K) gold.
Because 24K gold is soft, it's usually mixed with other metals to increase
its hardness and durability. If a piece of jewelry is not 24 karat
gold, the karat quality should accompany any claim that the item is
gold.
The karat quality marking tells you what proportion of gold is mixed
with the other metals. Fourteen-karat (14K) jewelry contains 14 parts
of gold, mixed in throughout with 10 parts of base metal. The higher
the karat rating, the higher the proportion of gold in the piece of
jewelry.
Most jewelry is marked with its karat quality, although marking is
not required by law. Near the karat quality mark, you should see the
name or the U.S. registered trademark of the company that will stand
behind the mark. The trademark may be in the form of a name, symbol
or initials. If you don't see a trademark accompanying a quality mark
on a piece of jewelry, look for another piece.
Platinum is a precious metal that costs more than gold. It usually
is mixed with other similar metals, known as the platinum group metals:
iridium, palladium, ruthenium, rhodium and osmium.
Different markings are used on platinum jewelry as compared with gold
jewelry, based on the amount of pure platinum in the piece. The quality
markings for platinum are based on parts per thousand. For example,
the marking 900 Platinum means that 900 parts out of 1000 are pure
platinum, or in other words, the item is 90% platinum and 10% other
metals. The abbreviations for platinum - Plat. or Pt. - also can be
used in marking jewelry.
The words silver or sterling silver describe a product that contains
92.5% silver. Silver products sometimes may be marked 925 which means
that 925 parts per thousand are pure silver. Some jewelry may be described
as silverplate: a layer of silver is bonded to a base metal. The mark
coin silver is used for compounds that contain 90% silver. According
to the law, quality-marked silver also must bear the name or a U.S.
registered trademark of the company or person that will stand behind
the mark..
TAKING THE GUESSWORK OUT OF DIAMOND BUYING.
Most people know little or nothing about diamonds. That's why the
American Gem Society came into existence over 70 years ago. Thanks
to Society members, we now have precise standards for evaluating diamonds,
commonly known as the 4 Cs: Cut, Color, Clarity, and Carat Weight.
The American Gem Society Diamond Grading Standards evaluate three of
the four value factors — cut, color, and clarity — on its
own 1–10 scale. The scales begin at 0 (zero), the highest grade,
and go down to 10, the lowest. The three factors are expressed separately
along with the fourth factor, the carat weight of the gemstone, for
the final American Gem Society Grade.
THE SCIENCE OF DIAMONDS.
While not everyone will share the same opinion as to what constitutes
beauty, most people want a diamond that expresses their individual
taste and personality. Here’s what you should consider first,
however, before buying a diamond:
Cut. Of all the 4 Cs, cut has the greatest effect on a diamond's beauty.
In grading, cut evaluates the cutters skill in the fashioning of the
diamond.
Diamonds have a unique ability to manipulate light efficiently. This
unique ability can be released and maximized only by cutting and polishing
the diamond to an extremely high level of accuracy. The American Gem
Society Cut Grading System considers not only the proportions of a
diamond, but also the craftsmanship of its overall symmetry and polish.
It is unique in that it uses the latest in technology to analyze the
cut’s impact on the diamond’s light performance.
Color. A truly colorless diamond is extremely rare. Most diamonds
possess varying degrees of yellow or brown and small, subtle differences
in color can make a substantial difference in value. If a diamond is
well cut, the diamond's refraction and dispersion often will disguise
certain degrees of coloration. Unless a diamond is a fancy color (or
any color other than colorless to light yellow or brown), the American
Gem Society Color Grading System places it on a 0 to 10 scale, 0 being
colorless. To accurately and consistently grade color, an American
Gem Society trained grader will utilize special lighting to compare
the diamond being graded to a set of American Gem Society Master Color
Comparison Diamonds, which have met exacting standards of cut, color,
clarity, and carat weight.
Clarity. Clarity is the evaluation of a diamond's internal and external
characteristics. The fewer inclusions or blemishes, the more desirable
the diamond. Inclusions are internal, that is, inside the diamond.
Crystals are merely minerals trapped inside the diamond; feathers are
breaks in the diamond. Blemishes are usually very small and are only
on the surface of diamonds. To locate these tiny characteristics, an
American Gem Society member jeweler will use a binocular microscope
that magnifies the diamond ten times. Then, evaluating the size, location,
nature, number, and color of all the inclusions and blemishes, a clarity
grade from 0-10 is assigned.
Carat. The standard used to measure diamond weight is the carat. A
carat equals 1/5 of a gram (or 1/142 of an ounce). Each carat is further
divided into points, each point representing 1/100th of a carat. While
weight may be the least important of the four Cs in determining value,
it may be the easiest of the four Cs to gauge accurately and is the
most objective. As diamonds increase in size, their cost tends to increase
geometrically. Thus, a one-carat diamond may cost more than twice as
much as a one-half carat stone of equal quality. Also, as previously
stated, weight does not always enhance the value of a diamond. In fact,
when a stone is improperly cut, added weight may serve only to reduce
its brilliance. For these reasons, you should consult with an American
Gem Society titleholder or individual regarding the question of carat
weight.
No Fear Diamond Buying:
What's the occasion? A birthday celebration? An important anniversary?
To declare, "I love you!" Or to ask, "Will you be mine
forever?" Whatever the emotion, nothing commemorates the moment
quite like a diamond. However, the one emotion that has no place in
the diamond-buying process is fear.
First, Buyer Beware.
If you're like most people, you know little or nothing about diamonds.
That's why the American Gem Society came into existence over 70 years
ago. Thanks to these gemological pioneers, we now have precise standards
for evaluating diamonds, commonly known as the 4 Cs: Cut, Color, Clarity,
and Carat Weight. The American Gem Society Diamond Grading Standards
evaluate three of the four value factors — cut, color, and clarity — on
its own 0–10 scale. The scales begin at 0 (zero), the highest
grade, and go down to 10, the lowest. The three factors are expressed
separately along with the fourth factor, the carat weight of the gemstone,
for the final AGS Grade. This "science of diamonds" helps
take the fear out of buying a diamond. |
GOBjewelry.com
