Understanding Diamond Carat Sizes
Carat weight is one of the most important of the four C's of a diamond. The
global standard to measure the weight of the diamond is in ‘Carat’. ‘Carat’ is a term used to describe the
weight of a diamond, and the word originates from Ceratonia siliqua, commonly known as the Carob tree.
Diamonds are sold by the carat (shown as ct.), a unit of weight, though it is often mistakenly seen in terms
of size. The difference is more than numerical. A 1-ct. Diamond weighs the same as four 0.25-ct. Diamonds,
but because it is so much rarer, the 1-ct. Diamond is more expensive than the sum of the
values of the 0.25-ct. diamonds. It is important to know that ‘Karat’ and ‘Carat’ weight are different words
that have a different meaning. Karat refers to purity in Gold and Carat is the unit of weight for
WHAT IS THE WEIGHT OF ONE CARAT?
A carat is a unit of measurement equal to 0.2gm or 200mg (equals one-fifth
of a gram). A carat is divided into 100 points (compare it to a dollar being divided into 100 pennies). For
example, a 40 point diamond weighs 0.40 carats. According to the US Federal Trade Commission rulings, all
weight representations are subject to a 1/200 carat (one-half point) tolerance.
A diamond's size is measured in millimeters, length by width or the diameter of the diamond. But two
diamonds of equal weight can have very different values depending on the other members of the Four C’s:
clarity, color and cut. The majority of diamonds used in fine
jewelry can weigh one carat or less. Diamonds are weighed with precision, right to the nearest
WHAT ARE DIAMOND SIZES?
Diamond Carat Weight Measures a Diamond’s Apparent Size
When viewing diamonds always check the measurements listed for each diamond to understand its size. The
length and width will tell you exactly how large the diamond will appear when viewed from above. Please keep
in mind while reviewing diamonds of any shape that increase in diameter of the diamond will yield a larger
increase in surface (crown) area and overall perceived size. It is best to check the measurements listed for
each diamond to understand its size. The length and width will tell you exactly how large the diamond will
appear when viewed from above. Two diamonds of the same shape and carat weight may still appear different in
size based on the cut proportions. A well cut diamond may even have a slightly lower carat weight than a
deeply cut diamond, yet still have a larger diameter, making it appear larger in size. Two diamonds of equal
carat weight may also appear very different in size based on the shape of the diamond. For instance, a 1
carat oval tends to appear larger than a 1 carat round. The chart below illustrates why. For each diamond,
the chart shows the following:
- APPROXIMATE SIZE
The diamond images online are shown as accurately as visually possible.
They are close approximation of the actual size of a 1 carat excellent cut for each shape. Visually, the
longer shapes (oval, marquise, pear, emerald) tend to appear larger to the eye than the round and square
The measurements correspond to the shape shown above, and are typical
for excellent cut diamonds of 1 carat weight.
- CROWN AREA - THE TOTAL SURFACE AREA (MM2)
The area gives the true size of the diamond face up (as it would appear
when set in a ring). For example, while the oval diamond image appears larger than the round image, the actual surface area
is the same for the two shapes, meaning the difference in size is one of perception, not reality. In
contrast, the oval not only appears larger than the princess cut, it actually has a larger surface area
(approximately 10% larger in this example), meaning the difference is not simply an
illusion created by the elongated shape.
WHAT DOES A DIAMOND CARAT COST?
The cost of a one carat diamond can range from just $1,500 to $18,000 for an
extremely well cut, high quality diamond. As the Diamond pricing increases exponentially as diamond carat
weight increases. That means once a diamond hits it’s critical weight, the price bumps up. The critical
weights are 0.30ct, 0.40ct, 0.50ct, 0.70ct, 0.90ct 1.00ct, 1.50ct, 2.00ct, 3.00ct, 4.00ct, 5.00ct and
10.00ct. As carat weight increases, you will typically pay more in total prices of the diamond and also on
a price-per-carat basis as well. Refer to the table below to understand the relationship between diamonds in
increasing carat weights and equal quality.
WHAT ARE “MAGIC SIZES”?
ome Diamond weights which are considered “magic sizes” include half carat,
three-quarter carat, and carat. Visually, there is negligible difference between a 0.99 carat diamond and
one that weighs a full carat. But the price differences between the two can be significant.
Diamonds that aren’t these “magic sizes” are called “off-size diamonds”
WHAT ARE “OFF-SIZE DIAMONDS OR SPECIAL SIZES”
Not every stone will fit into a whole or half carat size, but plenty do hit
those f ractions of carats — like a 1.3 or a 1.7 carat diamond. They aren’t as popular as their whole-size
counterparts, making it easier for you to get a larger weight stone for less money.
WHY ARE DIAMONDS SO EXPENSIVE?
For the diamond’s in today’s times, bigger isn’t always better. The
diamond’s value is assessed with the 4Cs - the diamond size (carat weight), colour, clarity and cut. The
larger the diamond, the higher the colour, the cleaner the diamond, the better the cut. The price is high
when the diamond is rare in nature and not easily available. It typically takes about 250 tons of rock
mining to produce a single 1 carat diamond. That's why diamonds are rare and expensive. If you want to
out a way to spend less but get a good diamond, consider getting to know about Magic Size and Off - Size