Diamonds - The 4Cs of Diamonds + More
eJeweller.com.au has produced this section
to provide you with a fair understanding of diamonds so you can make a more
informed purchasing decision. The 4Cs of diamonds are the criteria used by
diamond professionals to classify, grade and value loose diamonds. Each of the 4
Cs is described
in detail below. If you require further clarification of any aspect contact us
Jump to specific topic:
- Clarity - Carats - Cut
Save Money When Buying a Diamond
Glossary - Diamond Colour Chart - Diamond
Grades - Diamond Size Chart - Fancy
For the following discussion
please refer to the table on the right to visualize the diamond colour
corresponding to each letter of the scale.
In general, the less colour a diamond has, the greater its value. Colours
range from colourless (D) to light yellow (Z).
D - Absolutely
colourless, extremely rare diamond.
E & F - Still considered colourless, slight colour detectable
by an expert. Also a rare diamond.
G & H - Colour is noticeable when compared alongside a
I & J - Colour is slightly noticeable.
K to Z - Obvious and increasing amount of colour, diamonds less valued than
the ones above. After Z, as we move into the fancies, the diamond value starts to
increase again. We do not use or supply diamonds in this range at
Z+ - Diamonds in this colour range are called fancies. The most
rare and expensive fancy colours are Red and Green. Other colours include
Purple, Orange, Pink, Yellow and Black. Fancy diamonds are graded on a
different system with colour grades such as: faint, very light, light,
fancy light, fancy, fancy intense, and fancy dark.
When mounted in jewellery,
even G, H, I and J diamonds can appear colourless (especially when set in
yellow gold as opposed to white gold). It takes a highly trained eye to notice
the slightly yellow/brown tinge in them. For diamonds less than half a
carat that have been mounted in jewellery it is almost impossible for the
untrained eye to detect colour up to I. However the colour is there and
has an impact on the value of the diamond.
Colourless diamonds are extremely rare, and hence expensive, so most
diamonds in jewellery are 'near colourless' with extremely faint yellow/brown tints.
Despite the tint, 'Near Colourless' diamonds are considered to fall within
the 'normal' colour range. At eJeweller.com.au we use and supply diamonds
within the normal colour range but concentrate on the F - H range for our
online jewellery pricing which gives an excellent quality/value combination.
Diamond colour can be affected by treatments such as HPHT (High Pressure, High
Temperature Treatment) and Irradiation. Fluorescence can also affect
colour. More details follow.
Fluorescence is produced when UV light (eg. from the sun) hits a
diamond. It occurs in over 30% of gem-quality diamonds. The UV light
causes excitation of electrons in the diamond crystal producing a usually
blue light in varying intensities. When the UV source is removed so to
does the effect stop. The reason you should know about fluorescence is
that if strong it can alter the colour you perceive a diamond to be; ie
fluorescence can make top range colours (D - H) appear slightly cloudy (a
negative) whilst making lower grades (I - Z) appear to have less yellow
colour than they actually do (a positive). When buying a Diamond that has
fluorescence, make sure that it is blue and no other colour. If blue, it
won't be a factor in the stone's appearance unless the intensity grade is
strong or greater. Even in these cases it is rarely a problem and can in
some cases be a positive as described above. At eJeweller we tend to use
diamonds with Nil to Slight fluorescence.
Diamond Colour Treatments
High Pressure/High Temperature (HPHT) treatment
With this annealing process diamonds of low colour can be converted to
(D-H) colour. The technique has also been applied to Brown diamonds to
yield other fancy colours. Research shows that diamonds that have
undergone these treatments can be detected by sophisticated instruments.
This is a technique which uses a nuclear reactor to produce fancy
eJeweller.com.au we do not use any diamonds that have undergone
Colour's Effect on Price
As a very general rule of thumb you can expect a 1 carat diamond of J
colour to be 40-50% cheaper than the same diamond in a D colour.
Diamonds, being a
natural product, are subject to imperfections. Diamond Clarity grading is a system
that has been developed to categorise and describe these imperfections.
Refer to the chart on the right for a range of clarity grades used by the
GIA (Gemological Institute of America)
Types of Imperfections on Diamonds
The internal imperfections are broadly called inclusions, and the surface
irregularities are called blemishes. Taken together they are the 'clarity
characteristics' of the diamond. The following table categorises and
explains the various imperfections found in diamonds:
Abrasions - Small nicks on facet junctions or on the culet
caused by wear or rubbing against other diamonds.
Naturals - portions of the rough crystals surface left on the
finished diamond usually in the girdle.
Extra Facets - Small facets created to remove imperfections
that are not part of the cutting style.
Polish Marks - Surface clouding caused by excessive heating
Polish Lines - Small parallel lines left by irregular
Surface Graining - Faint lines causing wavy or grooved
surfaces due to irregularities in crystal growth.
Rough Girdle - Caused by poor workmanship.
Bearding - Small feathers extending inward from a bruted
Cavities - Large/deep openings in the diamond's surface.
Chips - Small/shallow openings in the diamond's surface,
Clouds - Hazy or cloudy areas caused by numerous very small
Feathers - White and feathery cleavages or fractures.
Fractures - Breaks along planes other than cleavage planes.
Included Crystals - Mineral crystals, such as garnet or
peridot, contained within a diamond.
Indented Naturals - Natural rough surfaces that penetrate the
stone and can distort the girdle's outline.
Internal Graining - Regions of irregular crystal growth
appearing as milky or coloured lines & streaks. May also be
Needles - Needle shaped included crystals.
Pinpoints - Areas of minute pinpoint inclusions.
Twinning Wisps - Clouded areas produced by distorted crystal
Laser Drill Holes - A minute tube made by a laser. Resembles
Whilst inclusions decrease
the value of a diamond they are useful in that they allow a gemmologist to
identify a diamond using the unique combination of its inclusions.
Inclusions also make it possible to distinguish real diamonds from lab created
All other factors being
equal, the higher up the chart a diamond's clarity grade is the more
valuable it is. Diamonds between the grades of VVS1 and SI2 represent the
bulk of the retail market.
At eJeweller.com.au we use
and offer diamonds ranging from IF (Internally Flawless) to SI2 (Slightly
Included). Diamonds in the SI1-SI2 range represent exceptional value for
money. As a rough guide a FL diamond in the range of 0.50 carat to 1.0
carat can cost 50% to 100% more than an otherwise identical SI diamond. So
to save money whilst still getting a beautiful diamond at eJeweller.com.au
we recommend the SI grade. An SI2 diamond will rarely have inclusions
visible to the naked eye, and will be just as beautiful as a higher
clarity diamond. This is especially so as you go down in size from 1ct.
no inclusions or blemishes of any sort under 10X magnification when
observed by an experienced grader.
- Internally Flawless
inclusions when examined by an experienced grader using 10X
magnification, but will have some minor blemishes.
& VVS2 - Very Very Slightly Included
minute inclusions that are difficult even for experienced graders to
see under 10X magnification.
& VS2 - Very Slightly Included
minute inclusions such as small crystals, clouds or feathers when
observed with effort under 10X magnification.
& SI2 - Slightly Included
inclusions (clouds, included crystals, knots, cavities, and
feathers) that are noticeable to an experienced grader under 10X
I2, 13 - Included
inclusions, possible large feathers or large included crystals) that
are obvious under 10x magnification and may affect transparency and
This is the simplest of
the 4Cs and the only 'C' that is not subjective.
What is a Carat
A Carat or ct. is just a unit of measure for the weight of the diamond. It has
nothing to do with Carat/Karat as in 9 carat/karat or 18 carat/karat gold which is a
unit of Gold Purity. To learn about gold carats/karats click here.
One carat is equivalent to
200mg = 0.200 grams = 1/5th of one gram. ie 5 carats = 1 gram. Given it is
measured with precise weight scales there is no need for human judgement.
One carat is further broken up into 100 points. ie a 50 point diamond is
50/100 carats ie half a carat. Similarly a 0.10 carat diamond is the same
as a 10 point diamond.
Carat Weight, Value
Value does not increase proportionately with carat size. For example a 1
carat diamond does not cost twice as much as a half carat diamond, nor 4
times as much as a 25 point diamond. It costs much more because as
the size of a diamond increases so does its rarity. For example, at eJeweller.com.au
we would offer a certified 1/2 carat diamond for around a third of the
price of a 1 carat
diamond of comparable quality.
Further, when viewed from
the top don't expect a 2 carat diamond will look twice as big as a 1 carat
diamond. The chart on the right is a guide to diameter increases in
well-cut diamonds. As can be seen in the scale, a 2 carat round brilliant
cut diamond will have a diameter approximately 8.2mm and a 1 carat diamond
approximately 6.5mm. The reason is that the weight of a diamond is
proportional to its volume and not to its girdle diameter.
The diameter of a diamond will also depend
on the cut to a certain extent. The sizes given in this table assume a well cut stone. Deep
cut diamonds appear smaller than well cut (ie well
proportioned) diamonds of the same weight and conversely shallow cut
diamonds appear larger than ideal cut diamonds of the same weight. Read
more on cut further down.
Another thing to consider when purchasing a diamond is that there is a
premium price when they reach and exceed each 1/4 carat level. As an
example a 0.99 carat diamond will be cheaper per carat than a 1.00 carat
diamond. ie there is a larger jump in price from 0.99 carat to 1.00 carat
than there is from 1.00 to 1.01 even though in both cases the diamond is
only 0.01 carats bigger. So to save a little money, when looking for a 75
point diamond for example, you may as well buy a 73 or 74 point diamond if
one is available at a better price. Be
warned that some large online retailers offer 1 carat diamond rings and in
the fine print mention the stone could be a minimum of 0.98 carats. At
eJeweller.com.au if a ring is described as 1 carat we guarantee you will
get a 1 carat diamond ring and more often than not you will end up with
1.01 or 1.02 etc.
Cut is commonly confused with
shape. For a list of Diamond Shapes look to the list on the right.
The true meaning of cut in a diamond grading context is the various
proportions, symmetry and finish of the diamond. What makes evaluation of
cut so difficult is that there is more than one way, and many opinions, as
to how to cut a diamond to optimize its optical properties and hence
maximize its brilliance and beauty.
Proportion refers to the angles and relative measurements of a polished
diamond. More than any other feature, proportions determine a diamond's
optical properties. Scientific studies have shown that table size, crown
angle, and pavilion depth have a dramatic effect on a diamond's
Given this, cutting a diamond to produce the greatest possible return of
light to the observer depends on the interrelationship between these three
components. There isn't however just one specific combination of these
three that will yield the most brilliant diamond. Various combinations of
these proportions can potentially produce diamonds of equal brilliance and
The diagram on the
right only looks at pavilion depth (distance from the bottom of the girdle
to the culet), one of the 3 major proportions affecting a diamond's
brilliance. A pavilion depth that is too shallow or too deep will allow
light to escape from the side of the stone, or through the bottom, causing
a dark and dull appearance and reducing the diamond's brilliance. A
well-cut diamond will direct more light through the crown thus maximising
the brilliance of the diamond. Note
that the diagram is an oversimplified 2-dimensional representation of the
complex behaviour of light passing through the diamond which in reality
includes refraction, dispersion and reflection.
Symmetry refers to the exactness of correspondence and
alignment between facets of a diamond. Problems that diminish the
symmetry of a diamond, usually due to poor or careless workmanship, are:
off-centre table, off-centre culet, non-round or wavy girdle, non-parallel
girdle, non-parallel table, table not a regular octagon, misaligned
facets, misshaped facets, naturals and extra facets not graded under
clarity. Poor symmetry can cause light to be misdirected as it travels
into, through and out of the diamond.
Finish refers to the precision of the cut, the condition of the
girdle and the diamond's polish. The polish grade given to a diamond
describes the smoothness of the facets. Poor polishing can dull the
surface of the facet creating a dull sparkle. The diagram on the right
outlines the various facets of a round brilliant cut diamond. Often the
culet is left pointed and hence is not a facet, giving a total of 57 facets.
The girdle is sometimes faceted but these facets are not counted in the
Hearts & Arrows
Hearts & Arrows is an optical phenomenon which can arise when a
round brilliant cut diamond has been well cut. The diagram in the right
margin illustrates the phenomenon which can be viewed with a symmetry
Cut's Effect on
Price & Size
Well cut diamonds cost more for 3 reasons. The first is that they look
the most beautiful and hence are in greater demand. Secondly more skill
was used and time was expended by the diamond cutter to get all the
proportions and angles to fall within a desired range of values. Thirdly,
and probably most importantly, a larger stone is required to cut a
well-cut diamond than a poorly cut diamond of the same carat weight. ie
you lose more of the diamond in the cutting process because the cutter
concentrates not on getting the heaviest finished diamond out of the rough
diamond, but rather the most brilliant diamond.
As an example, a well cut 1 carat diamond
has a diameter of approx 6.5mm whereas a shallow cut 1 carat diamond will
have a diameter greater than this and so appear larger when looked at from
the top. This isn't as good as it sounds because you will be sacrificing
brilliance of the diamond for apparent size. These badly cut diamonds
often have a dull lifeless look known as "fisheye".
Conversely a deep cut 1 carat diamond will have a diameter less than 6.5mm
so you will be paying for a diamond that not only looks smaller than it
should, but also doesn't have the brilliance of a well cut stone. These
stones often have a dark dull area in the centre which is a phenomenon
known as "nailhead".
Sacrificing 3 of
In conclusion, it is very important to consider only purchasing a well-cut
diamond even if this is to the detriment of the other 3 C's. The better
cut will will make up for the lower clarity, colour and possibly size
in brilliance and beauty. Indeed bigger is not always better. A diamond
can have excellent colour, clarity and size, but if cut badly will lack
brilliance and beauty.
What do we mean by well cut?
There are many terms used to indicate how well a diamond is cut. For round
brilliant cut diamonds look for a "Cut" or "Proportions" grade of
Excellent, sometimes called Ideal. Very Good and Good cut grades offer
excellent value for money. Below these are Fair, Poor or Unspecified, be
weary of these unless of course that is what you are after and you are not
being charged a premium. NB that the above grades are usually only
provided on certificates for Round Brilliant Cut stones. For fancy shapes
you will have to rely on your own knowledge and the trustworthiness of the
NB The above sections have
focused on the Round Brilliant Cut Diamond, but the most general
principles apply to all fancy cut diamonds as well.
How to Save Money on a Diamond
After reading and digesting all of the above
information you are now in a better position to make a diamond purchase. Whether
you buy your diamond from us at eJeweller.com.au or elsewhere we urge you to
keep the following tips in mind, they could save you some money.
Don't get hung up on the nice round numbers like
0.50 carat 0.75 carat and 1.00 carat etc. You can often save a few dollars by
purchasing 0.48 carat, 0.73 carat, and 0.99 carat. No human can tell the
difference between a 0.99 carat and a 1 carat diamond, yet you'll be saving more
than 0.01 carat difference because there is usually a disproportionate jump in
price when diamond sizes reach these 'milestone' sizes.
Further savings can be made by not going for the top colour. Unless you are a
purist, or have unlimited money, there really is no reason to buy a D colour
diamond given the premium price you must pay. Buying E or F colour will give you
a small saving, whilst buying a G or H colour diamond will save you a lot. Bear
in mind that G - J colour diamonds are still considered near colourless. A G-H
colour is still quite a high colour grade so you don't compromise too much on
quality whilst making a substantial cost saving. With I to J you can make
further savings but at this point the yellow colour is slightly noticeable in
a white gold ring setting,
however, if the diamond is to be set in a yellow gold ring or jewellery it will be
unnoticeable to the untrained eye. Savings of up to 50% can be made dropping
from colour D to colour J on a 1 carat diamond.
Clarity is another potential money saver.
Slight inclusions/impurities in the diamond don't really have a major effect on the path of light
through it until you get into the heavily Included grades (I1, I 2, & I3). This
means that brilliance of a diamond isn't greatly affected when going from FL
(Flawless) Grade to SI2 (Slightly Included) Grade. You are better off making a
saving here and using the money to purchase as good a cut as you can afford. As
an example you can save up to 50% by dropping from a clarity of FL to SI when
considering a 1 carat well cut diamond.
Cut is one area where we do not recommend you
make a saving. A very badly cut diamond will look dull and lifeless no matter
how many carats it is, how good a colour grade it has, and how much clarity it
has. Whilst you can compromise on the other 3 Cs you should really not
compromise on Cut. Insist on a cut of at least Good, Very Good is even better,
and if you can afford it Excellent (sometimes called Ideal). You will be glad you make this
So, if for example you were looking to buy a 1
carat Internally Flawless, D colour Diamond you could make very substantial
savings without a noticeable loss of beauty, by instead opting for a 0.95 carat, H
colour, SI2 diamond. The huge savings could then be used to try and obtain the
best cut you can afford, for example VG or EXC cut. This would give
you, in our opinion, a most beautiful diamond at an affordable price.
At eJeweller.com.au we stock and use GIA
Click here to view our huge range of loose
Diamonds with full details and pricing
available for online purchase.
Don't hesitate to contact us for further
explanation of any of the above topics on firstname.lastname@example.org.
Glossary of Diamond Terms
Bruting - the first process of cutting a diamond by shaping its girdle
Optical Properties - the properties that determine light's interaction
with the diamond.
Brilliance - the combination of all the reflections of light from the
surface and from within the stone giving a stone its brightness.
Dispersion - also referred to as fire, the separation of white light into
its spectral (rainbow) colours caused by refraction, ie each colour having a
different wavelength to the others, will refract a little differently leading to
the separation of individual colours.
Scintillation - also referred to as sparkle,
tiny flashes of light observed with movement of either the light source, the
diamond or the observer's eye.
Fancy Cuts - Shapes other than the standard
round brilliant cut are referred to as fancy shapes or cuts
More Diamond Facts
1. Diamond's tight crystalline structure slows
light down like no other substance can.
2. Light inside a diamond travels at less than
half its speed through a vacuum.
3. Diamond is the hardest naturally occurring
4. Diamond is a crystallized carbon mineral.
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Have received our rings today, and could not be more thrilled!!, the
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done. The rings are beatiful and the only disappointment is that i
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Thankyou once again,