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Diamond Guide

Before buying a diamond there is a set of assessment guidelines that may help you.

At Dulong, we use the famous four Cs in order to assess our diamonds. The wellknown four Cs stand for Cut, Colour, Clarity, and Carat.

In addition, Dulong has expanded the assessment scale with two extra Cs, which stand for Confidence and Charisma.

Please find answers to some of the most frequently asked questions by our customers below.

What are diamonds made of?

Although the diamond must be the world’s most desired stone, it is made out of something as modest as carbon.

During the course of billions of years, natural diamonds are created deep underneath the surface of the earth by enormous heat and pressure. Slowly, they are carried upwards, towards the light by deep volcanic eruptions and are finally mined by man.

The violent pressure and heat that the diamond has been exposed to makes the diamond the hardest known mineral in the world and consequently a diamond can only be cut by another diamond.


How do you determine the value of a diamond?

Diamonds are valuable and in order to streamline the assessment process, an international set of rules have been agreed in terms of determining the value of diamonds. In this way, you’re able to compare the price of diamonds across borders and cultures.

Diamonds are assessed on the basis of the four Cs:

  • Carat (weight)
  • Colour
  • Clarity
  • Cut

Kharisma Supernova


Carat describes the weight of a diamond.

1 carat = 0,2 gram

Carat is one of the most important factors in the assessment of a diamond’s value. Carat equals the weight of the diamond and plays an important part in the determination of the value. The general rule is that the larger and heavier the diamond is, the more valuable is becomes.

However, it’s important not to mistake carat for karat (US spelling) or gold carat (UK spelling) as they are two different terms. The weight of a diamond is measured in carat, not to be mistaken for karat or gold carat, which are the terms for the quality of gold, e.g. 18 karat gold. This can be pretty confusing as the word is spelled the same way in some countries.



Colour describes the colour of a diamond.

Most of us can recognise a classic white diamond but a diamond may have many different shades and colours.

The two most established grade systems to determine the value of a diamond in Europe and the US are GIA, short for The Gemmological Institute of America and Scan D. N, an abbreviation of Skandinavisk Diamant Nomenklatur.

In these two systems, the white, classical diamond has its own colour scale.

In addition, you’ll find diamonds in fascinating colours like steelgrey, blue, orange, red, green, pink, purple and black. Natural coloured diamonds contain small impurities and structural flaws that create the colour and previously coloured diamonds haven’t been regarded as valuable as colourless, white diamonds. However, in recent years there’s been a great shift in opinion and today naturally coloured diamonds are among the most popular and expensive diamonds.

Fancy colour diamonds

Natural coloured diamonds are sometimes of a quality called fancy colour diamond. Gem diamonds, e.g. in the GIA D-to-Z range traditionally decrease in value as the colour becomes more obvious. However, just the opposite happens with fancy colour diamonds: Their value generally increases with the strength and purity of the colour. Large, vivid fancy colour diamonds are extremely rare and very valuable.

Diamond earrings


Clarity describes the clarity of a diamond.

So-called inclusions are found in virtually all diamonds as they are the result of the stone’s formation process. Many of them are very small, in fact so tiny that they are only visible through a magnifying glass. The inclusions are important when determining a diamond's value because potentially the inclusions could block the reflection and shine of the stone if there are too many of them.

Clarity is based on an assessment system describing the inclusion in the diamond in terms of numbers, size, placement and visibility when looked at through a 10x magnifying glass.

The rarest clarity is Lup Ren.

Most inclusions aren’t visible to the eye before grade P. It’s important to add that the placement of the inclusions also has an impact on the assessment.

  • LC: FL-IF FLAWLESS: lupren, no inclusions
  • P 1 PIQUE 1: inclusions
  • P 2 PIQUE 2: visible inclusions
  • P 3 PIQUE 3: imperfect

Diamond guide


A diamond cut is a style or design used when shaping a diamond.

A raw diamond is beautiful but nonetheless it’s the cut that brings out the true charisma of the diamond. That’s why we’re willing to scarify as much as half the weight of the raw diamond as the cut compensates for the loss of weight in increased beauty.

Originally, the cut didn't mean the design of the cut but the quality of the cut. The quality covers the proportions and the finish and these two factors are essential for the result and the beauty of the diamond in the end.

For most diamond connoisseurs, the cut is the most important factor when determining the value of a diamond, but it’s also the factor, which is the hardest for the untrained eye to assess.

Over time, the Cut has become equal to the design and shape of the diamond cut. A number of beautiful cuts exist. Some of the most popular are the Brilliant Cut, The Princess Cut and the Cushion Cut.


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

Our customers often wonder about the difference between a diamond and a brilliant? The quick answer is that a brilliant is a diamond cut with the so-called Brilliant Cut - a cut which is also known as the perfect cut. The word brilliant originates from the French word brilliant, which means radiant. A Brilliant Cut consists of 57 facets, which creates a beautiful, dynamic fire inside the diamond.

The Brilliant Cut is the most popular and coveted cut in the world because it has a radiance second to none. At Dulong, all diamonds are brilliants.

Harmony Diamond Ring with 13 sparkling brilliants


The brilliant cut. The optimum cut.

The original brilliant cut was developed by Marcel Tolkowsky in 1919 and revolutionised the cutting of diamonds. Up to that point, no jeweler had been able to create such a powerful inner light in a diamond. The round brilliant cut consists of 57 facets. Originally there were 58 facets and this type of cut is now called ”old cut”. Most jewelers omit the so-called culet today, which is the original 58th facet.

On your right, you’ll find the ”old cut” and on your left you’ll see the very popular modern round brilliant cut. Many jewelers regard The Brilliant Cut as the optimum cut.

Briolette Diamonds

What are briolette diamonds?

Briolette diamonds have a breathtaking, drop-shaped cut. This is one of the oldest gemstone cuts, and we have rediscovered its charm in recent years. One senses the aura of history when admiring the superb, classic shape of briolette diamonds. In the Victorian era, they were highly sought after, and Napoleon Bonaparte gave his beloved Empress Marie Louise a magnificent necklace with diamonds in this iconic cut. Today, this piece is on display at the Smithsonian Museum, where visitors can marvel at the necklace’s 55 carats and exquisite craftsmanship.

Briolette Diamonds are particularly suitable as pendants on either a necklace or bracelet. The briolette is a feminine and refined cut that artfully reflects light from many angles.



Trust and professionalism are paramount when you invest in a piece of diamond jewelry.

It may prove confusing to decide on the quality of the diamond and it requires practice to determine the value of the stone. At Dulong, our staff are trained in Antwerpen and we only use GIA certified diamonds when selecting large diamonds. In addition, we have some of Denmark’s finest and most skillfull goldsmiths employed to ensure that our diamonds get the space and frame they deserve.

There’s also a moral issue in terms of the so-called ”blood diamonds”. At Dulong, it’s important for us to know the origin of our diamonds and we only buy from conflict free areas in line with the UN resolution.

All diamonds above 0,5 carat from Dulong come with a GIA certificate.  

Kharisma øreringe med diamanter


Charisma stands for the overall impression of a diamond.

The four Cs may give you an objective assessment of a diamond, but they cannot tell you the full story of the diamond. That’s why we have introduced a concept, we call Charisma. Diamonds that are graded equally on paper may be very different in appearance and beauty due to a variation in the placement of inclusion and inner light.

It’s important to understand that diamonds are natural stones with their own expression, fire and sparks. Each stone must be evaluated individually and at Dulong we probably see 150 stones for each five we chose.

The most important thing for us is to find the most charismatic diamonds, which will provide our customers with the best value for money.

Diamond ring

How do you clean diamonds?

It's a good idea to clean your diamond jewelry on a regular basis as e.g. soap and cream easily stick to diamonds thus preventing the light from reflecting through your beautiful stones. 

In order to clean your diamonds, you'll need:

  • a small bowl
  • detergent
  • a soft brush
  • a soft cotton cloth

Use the small bowl to avoid dropping your jewelry in the zink or in the drain. Diamonds tolerate soap and detergent, which are the most effective way of cleansing together with hot water and a soft brush.   After cleaning the diamonds, use the small cloth to prevent chalk stains. 

Diamond ring

Diamonds from Dulong

You'll find a selection of Dulong's beautiful diamond rings here:  Diamond rings

The beautiful Halo diamond ring from Dulong with 17 diamonds in gold 18 Karat. 

Kharisma fra Dulong

Jewelry from Dulong

Dulong is known for the iconic and coveted Kharisma earrings. On your left, the beautiful Kharisma Supernova earrings with 334 diamonds.

"Many gemstones are as beautiful as the diamond but none possesses the same power"

Marianne Dulong

Diamond guide! How do you determine the value of a diamond? What does the four Cs stand for? How many different cuts are there? Find answers about diamonds right here!