Diamond Guide: The 4Cs, Shapes and Certificates

Brilliant or Rose Cut?

Every diamond is the same stone; what shapes its look is the cut. Most diamonds today are cut as brilliants: a round brilliant has 57 or 58 facets, arranged to send as much of the light entering the stone as possible back to your eye. Oval, pear and princess diamonds are brilliant cuts too.

Long before the brilliant, jewelers used the rose cut: a flat base under a dome of small triangular facets. It returns less light than a brilliant but has a soft, warm glow, and it is the cut of traditional Ottoman jewelry. Our Rose-Cut Diamond collection carries that tradition on from the Grand Bazaar.

The History of Diamonds

The story of diamonds begins more than 2,000 years ago in India, in the gravel of its riverbeds. For centuries they were stones for rulers alone. Finds in Brazil in the 18th century and in South Africa at the end of the 19th century brought them within reach of many more people.

The first known diamond engagement ring dates from 1477, when Archduke Maximilian of Austria gave one to Mary of Burgundy. The round brilliant we know today took shape in 1919, when Marcel Tolkowsky calculated the proportions that return light best.

Istanbul has its own chapter in this story: a few minutes’ walk from our atelier, the Treasury of Topkapı Palace displays the 86-carat Spoonmaker’s Diamond (Kaşıkçı Elması), one of the most famous diamonds in the world.

What Diamonds Mean

The word diamond comes from the Greek adamas, meaning invincible. As the hardest natural material, the diamond has stood for strength and permanence for centuries.

A solitaire for a proposal, a five-stone ring for an anniversary: a diamond is a way of saying “forever” at life’s most important moments. It is the birthstone for April, and the 60th wedding anniversary is the diamond anniversary.

Natural diamonds formed about 90 to 120 miles (150 to 200 km) below the surface, under immense pressure and heat, between 1 and 3.5 billion years ago. The stone on your finger is one of the oldest gifts on earth.

What Are the 4Cs?

Every diamond is described by four characteristics, known as the 4Cs. GIA (the Gemological Institute of America) created the system in the 1950s, and today it is the common language of jewelers around the world.

Carat: the stone’s weight
Color: how colorless the stone is
Clarity: the natural marks inside the stone
Cut: how well the stone returns light

No single C makes a beautiful diamond; what matters is the balance of all four.

Carat

Carat is the unit of weight for diamonds: one carat is 0.2 grams. It is not the same as karat, which measures the purity of gold: 14K and 18K tell you how much pure gold the metal contains, not how much it weighs.

As the carat goes up the stone grows, but not at the same rate: when the weight doubles, the diameter grows by only about 25%. Two stones of the same carat can also look different in size depending on their cut and shape. Move the slider to see how each carat weight looks on the hand.

1,00 ct ≈ 6,5 mm

Actual Size on Screen

Approximate; every screen displays at a different scale. Calibrate your screen with a bank card

Illustrative: a well-cut round brilliant on an average ring finger.

Color

Diamond color is graded with letters from D to Z. D is completely colorless; further down the alphabet a faint yellow tone appears. The differences are very fine and often show only when stones sit side by side under an expert’s eye.

D–F are colorless and G–J near colorless. In white gold a G–H stone looks colorless on the hand, while yellow and rose gold naturally balance the warmer tone of H–J stones.

Color is easier to see in larger stones. Step cuts such as emerald and Asscher show color more; round, oval and cushion cuts hide faint tones with their sparkle.

K–M: Faint · N–Z: Very Light to Light

Hover over or tap a letter to see what each color grade means.

Clarity

Most natural diamonds carry tiny marks from the time they formed. These are called inclusions, and they give each stone its own character; the most common are crystals, feathers and clouds. Clarity is graded by how visible these marks are under a 10x loupe.

Jewelers often use two terms. An eye clean stone shows no marks to the naked eye; most VS2 and SI1 stones are eye clean. A loupe clean stone shows none even under a loupe; FL and IF belong here. In the I1–I3 grades, inclusions can be seen with the naked eye.

Where an inclusion sits matters as much as its size. A mark in the center of the stone catches the eye at once; one near the edge often hides under a prong. Sparkling shapes such as oval, cushion, pear and marquise hide inclusions well; emerald and Asscher cuts show the inside of the stone more clearly, so a higher clarity is preferred. The larger the stone, the easier inclusions are to see.

FL Flawless. Nothing visible inside or on the surface, even at 10x.
IF Internally flawless; only tiny surface marks.
VVS1 Very, very small inclusions; hard to see even at 10x.
VVS2 Very, very small inclusions; hard to see even at 10x.
VS1 Small inclusions; visible with a loupe, not to the eye.
VS2 Small inclusions; visible with a loupe, not to the eye.
SI1 Easy to see with a loupe; usually not visible to the eye.
SI2 Easy to see with a loupe; usually not visible to the eye.

Cut

Cut has the greatest effect on a diamond’s beauty. Its proportions, symmetry and polish decide how the light that enters the stone comes back out. A well-cut diamond gives white brilliance, rainbow-colored fire and sparkle with every movement.

In a stone cut too deep or too shallow, light escapes through the sides and bottom and the stone looks dull. GIA and HRD grade round diamonds as Excellent, Very Good, Good, Fair or Poor. A stone graded Excellent for cut, polish and symmetry is called 3EX.

FairSome light escapes through the sides and bottom; the stone looks dull.
GoodMost light returns, but brilliance stays limited.
Very GoodLight largely returns to the top; a lively sparkle.
ExcellentNearly all light returns; the most brilliance and fire.

Parts of a Diamond

Diamond Shapes

Shape is the outline of the stone seen from above; it is not the same as cut quality. Round sparkles the most and is the most popular choice for solitaire rings. Oval, pear and marquise look larger at the same carat and make the finger look slimmer. In emerald and Asscher cuts, the step-like facets bring out the stone’s clarity more than its sparkle.

Round
Oval
Pear
Marquise
Heart
Princess
Cushion
Emerald
Radiant
Asscher

How to Choose a Diamond

Choose the design first. Solitaire, five-stone or eternity: the design decides the size and number of stones.
Don’t compromise on cut. Cut affects sparkle the most; choose Very Good or Excellent.
Match the color to the gold. D–H looks beautiful in white gold, G–J in yellow and rose gold.
An eye clean stone is usually enough. In a stone that looks clean to the naked eye, a higher clarity grade makes no visible difference; VS2 and SI1 are a good place to start.
Think about carat in proportion to your hand. A stone looks larger on a slender finger, and the difference between 0.90 and 1.00 carat is almost impossible to see.
Ask for the report. An independent laboratory report documents the stone’s qualities.

Certificates and Grading Reports

A grading report shows that a stone has been examined by an independent gemological laboratory. It records the carat, color, clarity, cut, measurements, fluorescence and a report number. On many stones the report number is laser-inscribed on the girdle, and you can look it up on the laboratory’s website.

GIA (Gemological Institute of America, United States): the institute that created the 4Cs.
HRD Antwerp (Belgium): one of Europe’s leading diamond laboratories.
IGI (International Gemological Institute): the report most widely used for lab-grown diamonds.

Every Joy piece ships with a Joy certificate issued by our atelier. Diamonds of 0.50 ct and above also come with an independent report: HRD or GIA for natural diamonds, IGI for lab-grown diamonds. Each product page states the report that comes with the piece.

Natural and Lab-Grown Diamonds

A lab-grown diamond is the same material as a natural diamond: pure carbon, with the same hardness and the same brilliance. It is grown in a few weeks by HPHT or CVD, and only laboratory instruments can tell it apart from a natural diamond.

What sets them apart is origin and rarity: a natural diamond formed deep in the earth over billions of years, while a lab-grown diamond is created in a controlled environment. A lab-grown diamond is not a simulant like cubic zirconia or moissanite, and its report states that it is laboratory-grown. On our site, lab-grown diamonds are always named as such and have their own collection.

Caring for Your Diamond

Clean your diamond with warm water, a few drops of mild soap and a soft toothbrush, then dry it with a lint-free cloth.
Keep it away from bleach and pool chlorine; these chemicals can damage gold.
Take it off for sports, heavy work and cleaning. Put on creams and perfume before your jewelry.
A diamond can scratch other jewelry, so store your pieces in separate compartments.
Have the prongs that hold your stone checked once a year. Our atelier cleans, polishes and checks Joy pieces free of charge for as long as you own them; you cover insured shipping.

Frequently Asked Questions

Can a diamond break?

Diamond is the hardest natural material and does not scratch easily. A hard knock, however, can chip or break it, especially at the edges. That is why we recommend taking it off for sports and heavy work.

Does a diamond change color over time?

No. A diamond’s color and brilliance are permanent. If a stone looks dull, the cause is oil and dirt on its surface; a simple cleaning brings back its first-day sparkle.

How can I tell if a diamond is real?

The most reliable way is to buy a diamond with a report from an independent laboratory such as GIA, HRD or IGI. The testers jewelers use also give a quick check. Fog and water tests at home are not reliable.

Can a lab-grown diamond be told apart from a natural diamond?

Not with the naked eye or a loupe; only the specialist instruments of a gemological laboratory can tell them apart. That is why the stone’s origin is stated clearly on its report.

Are carat and karat the same thing?

No. Carat is the weight of a diamond. Karat, written 14K or 18K, is the purity of gold; the weight of the gold is measured in grams.

Diamond Glossary

Short explanations of the terms used in this guide. You can also hover over or tap any term marked (i) in the text to see its explanation.

Rose Cut: A cut with a flat base and a dome of small triangular facets. In use since the 16th century and common in Ottoman jewelry. It returns less light than a brilliant, with a soft, warm glow.
Facet: The small flat surfaces cut into a stone. A round brilliant has 57 or 58 facets; they reflect the light.
Inclusion: Tiny natural marks left inside the stone as it formed: small crystals, clouds or feather-like lines. They give every stone its own fingerprint.
Types of Inclusions: The most common: crystal (a tiny mineral trapped inside), feather (a fine crack-like line), cloud (a cluster of tiny pinpoints) and needle (a thin, long crystal).
Eye Clean: A stone with no inclusions visible to the naked eye at a normal viewing distance. Most VS2 and SI1 stones are eye clean.
Loupe Clean: A stone with no inclusions visible even under a 10x loupe. FL and IF grades belong here.
Loupe: The small 10x magnifier jewelers use to examine stones. Clarity grades are based on this magnification.
Fire: The rainbow flashes a diamond gives by splitting white light into colors.
3EX: Short for Excellent cut, polish and symmetry; the diamonds that return light best.
Fluorescence: A glow, usually blue, some diamonds show under UV light. Reports list it as None, Faint, Medium or Strong.
Girdle: The thin edge between the top and bottom of a diamond. The report number is often laser-inscribed here.
HPHT and CVD: The two methods for growing lab-grown diamonds: HPHT uses high pressure and temperature, CVD builds carbon up layer by layer.

Have a Question?

Our specialists answer every question on WhatsApp, and you are welcome to see the stones up close at our atelier in Istanbul’s Grand Bazaar.

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Diamond Guide