Diamonds are our most
popular gem. They have great brilliance, plus the delightful quality
know as fire, or dispersion. (That is the ability to take in white
light and throw back flashes of color.)
...Diamonds are graded into dozens of
categories. While this is helpful to the professional, it can be
confusing to the average consumer. I especially feel for the young
couple looking for their first diamond engagement set. They want to
gather enough information to make an intelligent decision, but can
be overwhelmed by all the data thrown at them.
...To help you I have done two things.
First, there is a description of how diamonds are graded. Once you
understand that, I make recommendations on chosing a diamond. Please
graded on four qualities, commonly known as the 4 C’s:
...The closer a diamond is to being
colorless, the greater it’s value. When the current grading system
was introduced in the 1930’s, diamonds were commonly called grade A,
B, or C. So the current system began color grading with the letter
D, to avoid any confusion.
... Colors D, E and F are the
highest grades. They are described as “near colorless.”
... Colors G, H, I and J come
next. They are described as “white.”
... The colors from K to Z are
tinted, (usually yellow or yellowish brown.) Those that are just
lightly tinted, K, L and M are often said to “set white.” That means
that they are so lightly tinted that they will appear white if set
in yellow gold. You would however notice their color if set in white
gold or platinum.
... As one gets further down the
alphabet, the tinting gets stronger and the value lower. That is,
until you get to the extreme. As the color becomes richer, you have
a fancy colored diamond, rather than an off colored one. Then the
value starts going up again.
... Color grading is done by placing a
diamond next to a set of previously graded gems. The color is
compared to the graded gems to see which it comes closest to
... While this low tech approach is
accurate, it is also expensive and time consuming. A compromise is
often made on smaller gems, by grading batches within a range,
rather than coming up with a specific grade. You will usually find
diamonds under a carat graded as GH, or IJ, meaning that they are in
... This information is meaningful and
saves you quite a bit of money. It costs over $100 to accurately
grade a diamond. If you have a large diamond, where subtle
differences in quality grades make a significant difference in
price, then it is worth while. However, that isn’t cost effective
for the majority of gems.
...The clarity of a diamond
is determined by the size and number of inclusions inside of it. An
inclusion can be another mineral, a fracture or occasionally a void.
Simply put, it is anything that will interfere with the free passage
... Just like with color, there are
many clarity grades. They are judged by what an expert can see at 10
power magnification, under ideal conditions. The highest grade a
diamond can get is Flawless. That means no inclusions can be seen at
10 power magnification. It does not mean inclusions can’t be found
with higher magnification, nor should you assume it is the only
grade with no inclusions visible to the naked eye.
... Clarity grades use the letters V, S
and I. They stand for Very, Small, and Inclusion. Progressing from
Flawless, the grades are VVSI1, (Very, Very Small Inclusions One,)
VVSI2, VSI1, VSI2, SI1 then SI2. These are the grades of diamonds
that have no “eye visible” inclusions, those that can’t be seen with
the naked eye. (Note, some SI2 stones will have small, eye visible
... As we progress down the grading
scale, there is I1 and I2. These have eye visible inclusions, but
are still considered to be gem grade.
... Then there is P1 and P2. They are
not usually considered gem grade because so little light will pass
through them. However, since they have the magic name diamond, they
do show up on the market regularly.
... Beware of ads “1 carat diamond
ring, $299.” Just because something is a diamond, doesn’t mean it is
a gem. In fact, the vast majority of diamonds mined are usually
considered “industrial grade” and are used as abrasives. Many of
these "industrial grade diamonds," those graded as P1 and P2, find
their way into jewelry simply because they had the advertising
appeal of being diamonds.
one of the hardest properties to judge, plus there are a number of
factors to consider. The first one has to do with the brilliance of
... The pavilion facets of the gem are
intended to act as mirrors, to reflect the light entering the stone,
back towards the observer. However, the angle they are cut at has a
lot to do with how efficiently they work. Note: If you are
unfamiliar with this terminology, see our article on “Gem Cutting
... The ideal angle for diamond
pavilion facets is 41 degrees. This is usually quite convenient,
based on the shape of a standard diamond crystal. Unfortunately, not
all mined diamonds are in excellent proportions. The diamond cutter
is often faced with having to compromise between maximum brilliance
and maximum yield. The economics are such that, if the cutter
removes too much material from the original crystal, there is no
profit in it. Hence, many diamonds get cut at less than ideal
... Diamonds have a high refractive
index, which gives them their great brilliance. A little cheating
here or there is insignificant. However, if the cutter varies a
little further from the ideal the brilliance begins to suffer. Still
more and you get a gem that just doesn’t stand up to others in terms
of brilliance or fire.
... There are no standards for this.
Most jewelers are familiar with correct proportions and can judge it
from the shape. The best test for most of us is to simply compare
the gems side by side. If you have two diamonds of the same grade
and one is significantly brighter than the other, the cut is the
... Please understand that the above
discussion assumes we are talking about round diamonds. Because of
their symmetrical proportions, all the major facets can be cut at
the same angle. The same does not hold true for other shapes.
... Many people prefer a marquis shape. This
is fine, but do not expect a marquis, or any other shape, to be as
brilliant as a round. On a marquis it is necessary to cut a number
of facets to accommodate the shape. The angles these facets get cut
at vary, slightly to greatly, from those that give the greatest
brilliance. This is a simple fact of physics: the more facets that
are cut at the ideal angle, the greater the brilliance of the gem.
... When looking for diamonds you may
come across the terms, "Single Cut,” “Old Mine Cut” or “European
Cut.” These are gems that only have eight facets running from the
girdle down and eight up to the table. That makes a total of 17
facets. A standard round brilliant cut has 57 facets.
...These “single cuts” are usually used
on small accent stones, but occasionally you will find an older
diamond of decent size with this cutting. Obviously, these gems
won’t have the brilliance of a full cut diamond, therefore they
aren’t worth as much.
... Another factor that comes under the
heading of cut have to do with the shape of the gem. An ideal cut
gem should be symmetrical, not lop sided. This point should be
obvious, but sometimes it is helpful to point it out. A
misproportioned gem can be camouflaged in it’s setting and you might
not notice it until you have paid for it. This may not bother you,
but it might lead to dissapointment.
... Though hard, diamonds are also
somewhat brittle. (If this doesn’t make sense to you, see the
Hardness and Wearability. The girdle of the gem is the widest
part when viewed from the top and the thinnest when viewed from the
side. If cut too thin, it can present a weak area that is just
asking for trouble. These illustrations will give you an idea of
what normal proportions are. Some girdles get cut to a knife edge
and this is definitely something to be avoided.
...This is by far the easiest
of the factors to understand. Simply put, smaller diamonds are more
common than large ones. Therefore smaller diamonds cost less per
carat than large ones.
... If you were to see a diamond
broker's price list, under each grade, the price per carat would go
up with size. A grade of diamond that would cost $900 per carat in
the ½ carat size might cost $1100 per carat at ¾ of a carat and
$4000 in a full carat.
CHOOSING A DIAMOND
... You should spend six months
income on an engagement ring. I know that, I heard it on television!
For a salesman that is a great idea. However, picking a diamond is
something much more personal than finances.
... Economics vary from person to
person and family to family. I wouldn’t presume to advise you on how
much you can afford, but I can help you wade through the morass of
grading information and put it in common language.
... As a rule, I suggest diamonds that
are in the white range of color, (G, H, I or J,) and those with
clarity grades SI1 or SI2. Visually these are wonderful diamonds.
They are bright and lively they will dazzle all your friends!
... You might consider a lower grade of
color if the right deal was presented to you. An L graded diamond
can look white in a yellow gold setting and be quite brilliant. The
fact that it costs less per size might be worth your while. I
wouldn’t recommend looking for this grade, but if you found one in a
setting that you really love it would be worth serious
... Going down in clarity grading can
occasionally be worth your while too, depending on the individual
diamond and setting. Sometimes the “eye visible” inclusion that got
it that ranking is insignificant and the overall appearance is still
... Going down further in quality is
rarely worth while. I know a lot of jewelers make their living by
supposedly underselling the competition, when in fact they are
selling lower grade gems. Without better quality diamonds near by to
compare with, the customer is often convinced they are getting a
great deal. The diamonds sparkle, the price and terms are just, oh,
... The disappointment comes later.
Imagine your fiancé showing off her engagement ring, (something they
usually get great joy out of,) only to find hers is dull compared to
those of her friends. You no longer have a great deal. The enjoyment
of the diamond goes way down when you compare a lower quality gem to
a good one.
... Please consider this factor
carefully! While choosing a diamond is a personal thing and not
everyone will have the same opinion, most folks will get more
enjoyment from a higher quality dazzler, than a larger but mediocre
... How about going up in quality? That
is a personal matter. If you get an emotional boost from owning the
biggest and the best and can afford it, then you certainly should.
However, for most people who simply want a fine gem on their finger,
it isn't necessary.
... People who are serious about their
diamonds and get to look at a lot of them, get a real joy out of
finding those rare gems that are nearly colorless or nearly clean
under magnification. These gems are much rarer and therefore demand
a higher price. But that does not mean they are much prettier, nor
does it mean that you will get more enjoyment out of them.
... If you were to set two well cut
diamonds side by side, one graded D, VVSI1 and the other G, SI1, you
would see very little, if any, difference with the naked eye. You
would have a strong emotional reaction when you heard the prices
... The point is simple, these are the
rarest quality gems and the difference is only apparent to the
sophisticated diamond appraiser who inspects them carefully with
... There is occasionally a difference
between a diamond graded SI1 and SI2. (SI1 is defined as “small
inclusions, somewhat easy to find.” SI2 is defined as “small
inclusions easy to find.”) When I look at a gem graded SI1 I usually
see something like the first illustration. One or two tiny dark
spots that have no effect on the brilliance of the gem.
... Those graded SI2 have inclusions
placed near the center where they are more visible, or many more of
them. Some gems graded SI2, like the first illustration, will have
no significant difference in brilliance. In an extreme case, where
there are many inclusions, (even though none are large enough to be
seen without magnification,) they may make up 5% or more of the
visible area. That means a 5% or more reduction in brilliance.
... One of the most important elements
of a diamond's appearance is the cut. This is a difficult element to
judge. Diamonds are rarely cut to ideal proportions, but they have
such high optical properties that most of them are still beautiful.
Without getting overly technical, you can judge the quality of
cutting by simply comparing diamonds side by side. Look for overall
brilliance and fire; those little flashes of color. If the diamond
you are considering does not have the sparkle of the other gems,
then keep looking.
... To summarize, it is usually best to
go with quality rather than size, but if your budget is limited the
rarest qualities may not be worth your money.
Facts about Diamonds
REFRACTIVE INDEX 2.417
SPECIFIC GRAVITY 3.515
CLEAVAGE Perfect 4 directions
HEAT SENSITIVE No
SPECIAL CARE INSTRUCTIONS None
ENHANCEMENTS Some colors produced by irridation, common.
Laser drilled to remove inclusions, common. Cracks filled with