Diamond guide

Before you buy a diamond or diamond jewelry, it's important to know a few concepts that can help you make the right choice.

First and foremost, you should know the 4 Cs. The 4 Cs stand for Cut, Colour, Clarity and Carat. These 4 grading parameters are recognised worldwide, and at Dulong we naturally use the well-known 4 Cs to describe our diamonds. 

Dulong has also expanded the rating with 2 additional Cs, which stand for Confidence and Charisma.

In our Diamond Guide, you'll find answers to some of the most common questions our customers ask about diamonds.

Halo diamond ring. White gold 18 K with 17 brilliant cut diamonds. With its vintage look, the classic, sparkling trilogy ring with Excellent Cut diamonds is a beautiful and iconic diamond ring.

What are diamonds made of?

The diamond is the world's most sought-after stone, but it's made from something as humble as carbon. Natural diamonds are formed when carbon is exposed to intense heat and pressure far below the Earth's surface over billions of years.

Since then, deep volcanic eruptions have carried them up towards the light, where we humans have found them. The intense pressure and heat to which the diamond has been subjected makes it the hardest known mineral in the world, and a diamond can only be cut with another diamond.

How do you determine the value of a diamond?

Diamonds are valuable, which is why a set of standardised rules have been established internationally on how to value diamonds. This way, diamond prices can be compared across countries.

Diamonds are generally valued based on what are known as the 4 Cs:

Carat (weight)

Glory Trio necklace with 3 brilliant cut diamonds.


Carat describes the weight of the diamond.

1 carat = 0.2 grams

Carat is one of the most important elements in the valuation of a diamond. Carat is a term for the weight of the diamond and thus helps to determine its value. The rule of thumb is that the larger the diamond, the more valuable it is.

It is important not to confuse carat with karat, as they are two different concepts. The weight of a diamond is measured in carat and should not be confused with karat, which is the term for the purity of gold, e.g. 18 karat gold. 

Kharisma Supernova diamond earrings with 334 diamonds.


Colour describes the hue of the diamond.

Most of us recognise the white diamond, but diamonds can have many different colours and shades.

There are several different scales for assessing a diamond's colour. The two most commonly used in Europe and the US are GIA, which is an abbreviation of The Gemmological Institute of America and Scan D.N., which is an abbreviation of Scandinavian Diamond Nomenclature.

The classic white diamond has its own scale in these two grading systems.

In addition, there are diamonds in fascinating colours such as steel grey, blue, orange, red, green, brown, pink, purple and black. Naturally coloured diamonds contain impurities and structural flaws that create the colour and therefore have not been considered as valuable as colourless white diamonds in the past. However, there has been a major shift in attitudes in recent years, and today, for example, pink and blue diamonds are extremely sought after and valuable.


Clarity describes the clarity of the diamond. 

There are so-called inclusions in virtually all diamonds, as they are a result of the stone's natural formation process. Many of them are so small that you can only see them with a magnifying glass. If they are hard to see, why talk about inclusions at all? The focus is on inclusions in the diamond because if there are too many of them, they can potentially block the stone's reflection and brilliance. 

Clarity is described on a scale where the inclusions in the diamond are rated by their number, size, location and visibility under a magnifying glass that magnifies ten times. The rarest clarity is Loupe Clean. 

Most of the inclusions cannot be seen at all with the naked eye. The inclusions usually only become visible to the naked eye in clarity P. It is important to add that the location of the inclusions also affects the assessment. 

LC: FL-IF. Loupe clean: flawless or internal flawless
VVS1-VVS2: very, very small inclusions
VS1-VS2: very small inclusions
SI1-SI2: small inclusions
P1 PIQUE 1: inclusions
P2 PIQUE 2: strong inclusions
P3 PIQUE 3: coarse inclusions

Luna Loop Diamond Earrings. Gold 18 K with pavé of 36 brilliant cut diamonds.


Cut describes the resulting proportions, polishing and pattern of facets and angles after the diamond has been through the hands of the diamond cutter.

A rough diamond is beautiful, but it is the cut that really brings out the best in the diamond. That's why people are willing to sacrifice up to half the weight of the precious rough diamond, because the cut compensates for the weight loss in increased beauty.

Cut did not originally mean the shape of the stone or the type of cut, but only the quality of the cut. Quality covers proportion and the so-called finish. The quality of these two factors is crucial to the result and thus the beauty of the diamond. 

There are five cut grades: Excellent (EX), Very Good (VG), Good (G), Fair (F) and Poor (P).

For most diamond connoisseurs, the cut is the most important factor when evaluating a diamond, but to the untrained eye, it is also one of the most difficult to assess.

However, the term cut has also come to refer to the shape of the diamond, and there are a number of different shapes.

The image shows some of the most popular cuts, such as Princess Cut, Oval Cut, Heart Cut and Cushion Cut.

What's the difference between a diamond and a brilliant?

We often get the question, "what is the difference between a diamond and a brilliant cut diamond?" The quick answer is that a brilliant is a diamond cut with the so-called "brilliant cut", considered by connoisseurs to be the most beautiful diamond cut. The word "brilliant" comes from the French word "brillant", meaning brilliant. A brilliant cut consists of 57 facets that create a brilliant inner fire in the diamond.

"The brilliant cut" is the world's most popular and sought-after diamond cut because no other cut creates the same brilliance. Therefore, the vast majority of diamonds in our jewelry are brilliant cut diamonds.

The Harmony halo ring with 13 beautiful brilliant cut diamonds.

What are briolette diamonds?

Briolette diamonds have a very beautiful, elongated pear shape and triangular or diamond-shaped facets. It's a classic cut that we've rediscovered in recent years, and there's a fascinating historical flavour to briolette diamonds when you look at the elegant, historic shape. 

In the Victorian period, they were highly sought after and Napoleon Bonaparte gave his second wife, Empress Marie Louise, a beautiful necklace with this enchanting type of diamonds. The necklace is on display at the Smithsonian Museum today, where all 263 carats and the impressive craftsmanship can be admired.

Briolette diamonds are particularly suitable as hanging pendants on either necklaces or bracelets. The word "Briolette" comes from French and in its original form means "small dried plum". The cut is a feminine and refined cut that beautifully reflects light from many angles. 

The brilliant cut. The optimum cut.

The original round brilliant cut was developed by Marcel Tolkowsky in 1919 and it revolutionised the cutting of diamonds, as it had never before been possible to create such a powerful inner light in a diamond. Today, the round brilliant cut consists of 57 facets. Originally, 58 facets were used, which is known today as the "old cut".

To the left is the so-called "old cut" and to the right is the very popular modern "brilliant cut".

Dulong has expanded the 4 Cs with two extra Cs that stand for:

– Confidence (trust in the dealer)
– Charisma (overall impression)


Trust and professionalism are essential when buying diamond jewelry.

Deciding on the quality of the diamond can be very confusing and it takes practice to assess a stone on different parameters. At Dulong, we have staff trained in Antwerp and we only use GIA-certified diamonds when selecting our larger diamonds. We also employ some of Denmark's most skilled goldsmiths, so our diamonds get the space and setting they deserve.

There is also a moral aspect to the so-called "blood diamonds". At Dulong, it is therefore important for us to know that our diamonds originate from orderly conditions. We ensure this by sourcing diamonds that are delivered in accordance with the UN Convention from conflict-free areas.

All diamonds over 0.5 carat from Dulong come with a GIA certificate. 

Glory Trio diamond earrings with 6 brilliant cut diamonds.


Charisma refers to the overall impression of the diamond.

The 4 Cs can tell you something about the objective judgement of a diamond, but they can't tell you the whole story of the diamond. That's why we at Dulong have introduced a concept we call Charisma. This means that diamonds with identical grades can be very different in their appearance in terms of the position and appearance of the inclusions.  

Diamonds are natural stones, each with their own expression, amount of fire, sparkle, etc. Every single stone needs to be evaluated, and at Dulong we probably see 150 stones for every 5 we select.

The most important thing for us is to find the diamonds that give our customers the best value for money.

Kharisma Diamond earrings with 10 brilliant cut diamonds. The iconic earrings come in many sizes and styles and can be accessorised with pearl or gemstone pendants.

How do you clean diamonds?

It's a good idea to clean your diamond jewelry regularly, as daily use will leave traces of e.g. soap residue and lotion on the diamonds. This prevents the light from finding its way into the diamond, and the diamond will not achieve its optimal brilliance and beauty.

Therefore, here's a quick and easy guide on how to clean your diamond jewelry.

Here's how to do it:

Use a small bowl to avoid dropping the ring down the sink or drain. Diamonds can withstand dish soap, which is the most effective form of cleaning when used with a soft brush. The soft brush makes it possible to get into corners and the underside of the jewelry. Finally, use a soft cotton cloth to wipe the jewelry to prevent limescale build-up.

Hand sanitiser is also an option, as diamonds are not damaged by alcohol, unlike pearls and other precious stones.

Trinità three-stone ring in 18 K white gold with 3 brilliant cut diamonds.

Diamonds from Dulong

Dulong creates iconic and diamond jewelry that is classic, raw and glamorous. At Dulong, you'll find diamond rings and jewelry that will last a lifetime and mark life's big moments. We can visit our collection of classic diamond jewelry here.

Here you can see the Eternity diamond ring: Eternity is an exceptional diamond ring with sparkling Excellent Cut diamonds that will make a statement on any woman's hand. The amount of brilliant cut diamonds varies with the size of the ring, the smallest comes with a total of 1.43 ct. diamonds set in 18 carat gold or white gold, which beautifully emphasises the brilliant cut diamonds.

Jewelry from Dulong

Dulong is best known for the iconic Kharisma earrings, available in many sizes and precious metals, in versions with or without diamonds. Here they are shown in the exclusive Kharisma Galaxy design, in 18 K gold with 84 brilliant-cut diamonds. They are adorned with Heart pendants in 18 K gold with diamond pavé, which is one of our many earring pendants.

See the entire Kharisma collection here.

Marianne Dulong

"Many precious stones are at least as beautiful as the diamond, but none exude quite the same power"