Coloured Diamond

Fancy-colour-Diamonds

A coloured diamond is a diamond that exhibits a hue other than the traditional colourless range. While most diamonds appear colourless or near-colourless, coloured diamonds come in a variety of shades, ranging from yellow, brown, and blue to rare colours like pink, green, and red. The colour in these diamonds is caused by elements or chemical processes during their formation, which result in various hues and saturations.

Key Types of Coloured Diamonds:
Yellow Diamonds:

Yellow diamonds are among the most common coloured diamonds and owe their hue to the presence of nitrogen atoms in the crystal lattice. The nitrogen atoms absorb blue light, resulting in the yellow colour.
These diamonds can range from light yellow to vibrant canary yellow.
Intensity and Saturation: The more intense the yellow colour, the more valuable the diamond. The colour is graded on a scale from light yellow to fancy vivid yellow.
Brown Diamonds:

Brown diamonds are also relatively common and are often referred to as chocolate diamonds or cognac diamonds based on their specific hue. The colour in brown diamonds is typically caused by plastic deformation during their formation, which results in the diamond absorbing blue light.
Brown diamonds can be found in various shades, including light brown, champagne, and rich cognac.
They are graded based on the depth of colour, with higher intensities like fancy intense brown being more valuable.
Blue Diamonds:

The striking blue colour of these diamonds is caused by the presence of boron atoms in the crystal lattice. Boron absorbs yellow and red light, leaving behind the blue hue.
Blue diamonds can range from light blue to vivid blue. The most famous blue diamond is the Hope Diamond, which is a deep blue.
The colour intensity plays a significant role in the value, with the more intense the blue, the more valuable the diamond.
Pink Diamonds:

Pink diamonds are some of the rarest and most sought-after coloured diamonds in the world. Their colour is thought to be the result of structural defects in the diamond’s crystal lattice, which causes the absorption of certain wavelengths of light.
The colour can range from light pink to vivid pink, with fancy intense pink diamonds being the most valuable.
Pink diamonds are primarily found in Australia’s Argyle mine, though the mine has since been closed, making these diamonds even rarer.
Green Diamonds:

Green diamonds derive their colour from the presence of natural radiation that causes the diamond to absorb certain wavelengths of light, leaving a greenish hue.
The green can range from light green to deep, vivid green. Natural green diamonds are quite rare and can be valuable depending on the intensity of the colour.
Treated green diamonds are also available, where the green hue is enhanced through a process known as irradiation.
Red Diamonds:

Red diamonds are among the rarest of all coloured diamonds, and their colour is often attributed to defects in the diamond’s crystal structure. The exact cause of the red colour is not fully understood, but it is believed to result from a particular defect that causes the diamond to absorb blue and yellow light.
The red diamond can range from light red to deep red, with the most famous example being the Moussaieff Red Diamond.
Due to their extreme rarity, red diamonds command extremely high prices.
Orange Diamonds:

Orange diamonds are rare and owe their colour to the presence of nitrogen atoms, similar to yellow diamonds. However, the arrangement of these nitrogen atoms results in a different colour spectrum.
These diamonds can range from light orange to deep fiery orange. The more intense the colour, the more valuable the diamond.
Purple Diamonds:

Purple diamonds are extremely rare and are often caused by a combination of structural defects and the presence of hydrogen during the diamond’s formation.
These diamonds typically show a mix of red and blue hues, which gives them a unique, vibrant appearance.
Colour Grading of Coloured Diamonds:
The grading system for coloured diamonds differs from that of colourless diamonds. Coloured diamonds are graded based on two main factors:

Hue: The colour of the diamond, such as yellow, blue, or pink.
Tone: The lightness or darkness of the colour (from light to dark).
Saturation: The intensity of the colour (from faint to vivid or intense).
Diamonds with more intense and saturated colours, especially those classified as fancy vivid, are typically the most valuable. Coloured diamonds are graded with terms like fancy light, fancy, fancy intense, and fancy vivid, where the more vivid the colour, the more valuable the diamond.

Factors Affecting the Value of Coloured Diamonds:
Rarity: The rarity of the colour is a major factor in determining the value of a coloured diamond. For example, red diamonds and blue diamonds are significantly rarer than yellow diamonds, making them more valuable.
Colour Intensity: The intensity of the colour (saturation and tone) greatly influences the price. Diamonds with vivid, deep hues command higher prices than those with lighter or less saturated colours.
Size: Coloured diamonds, like colourless diamonds, are valued by their carat weight. Larger coloured diamonds with strong, vivid colours are extremely rare and fetch exceptionally high prices.
Origin: Some coloured diamonds, like pink diamonds from the Argyle mine, are particularly valuable because of their rarity and the mine’s closure, making the diamonds even more scarce.
Treatments of Coloured Diamonds:
Some coloured diamonds undergo enhancement treatments to improve their colour. For example:

High Pressure High Temperature (HPHT) and irradiation are methods used to enhance the colour of diamonds, especially for those in the yellow, brown, and green ranges.
Natural coloured diamonds are often preferred for their uniqueness and value, as treated diamonds generally have a lower resale value.
The DCLA and Coloured Diamonds:
The DCLA (Diamond Certification Laboratory of Australia) offers colour grading for coloured diamonds using the standard grading scale and methodology, ensuring consistency with international grading systems. DCLA’s certification of coloured diamonds will include detailed colour information, including the hue, tone, and saturation of the diamond, providing buyers with a comprehensive understanding of the diamond’s quality and characteristics.

Annealing

artificially enhance the colour of a diamond

Annealing diamond refers to a process in which diamonds are heated to high temperatures in a controlled environment to alter their internal structure or appearance. However, diamond annealing is quite different from annealing in other materials, like metals, because diamonds are already a highly stable, hard material. The process is typically used to modify certain properties of the diamond, such as colour or internal inclusions, rather than improving the material’s hardness or strength.

Here are the key aspects of diamond annealing:

1. Annealing to Alter Colour:
Annealing can be used to change or enhance the colour of a diamond. This is often done to lighten or darken the stone’s hue, or to bring out more desirable tones, like in fancy colour diamonds.

Heating Process: The diamond is subjected to high temperatures (sometimes exceeding 1000°C) in a controlled environment, typically in a vacuum or in an atmosphere of certain gases, such as nitrogen or hydrogen.
Effect on Colour: The heat causes changes in the diamond’s crystal structure, which can alter how light interacts with the stone, thus changing its colour. For instance, diamonds with brownish hues may turn to a lighter yellow or even white, while others might enhance their natural colour intensity.
2. Healing Inclusions (Internal Cracks or Imperfections):
Another purpose of annealing is to reduce the visibility of certain inclusions, particularly graining or small cracks. In this case, annealing can:

Relieve Stress: The heat from annealing can relieve internal stress in the diamond, causing cracks or inclusions to become less visible. This is especially useful for diamonds that have inclusions located near the surface, which can affect the diamond’s clarity.
Mend Cracks: Under controlled conditions, the annealing process can sometimes cause minor surface fractures to heal by encouraging the material around the crack to bond back together.
3. Limitations and Risks:
High Temperature: Because diamonds are made of carbon in a crystal lattice structure, they can be sensitive to extreme heat. The temperature and environment must be carefully controlled during the annealing process to prevent damaging the stone. If not done properly, excessive heat can cause the diamond to fracture or even shatter.
Not Suitable for All Diamonds: Annealing is not always suitable for all diamonds. For instance, diamonds with a high degree of internal stress or fractures may not respond well to heat treatment, as the process could cause further damage.
4. Impact on Diamond Value:
Colour Alteration: If annealing is used to improve the colour of a diamond, it can enhance the stone’s appearance and potentially increase its value, especially for diamonds with rare or sought-after colours.
Clarity Improvement: If annealing successfully reduces the visibility of inclusions, it can improve the diamond’s clarity, which could also make the diamond more valuable. However, some buyers may be cautious about diamonds that have undergone treatment, as they may prefer natural diamonds without any enhancements.
Disclosure: When diamonds are annealed or treated in any way, it’s important for sellers to disclose the treatment. Some buyers prefer untreated, natural diamonds, and the presence of treatment may affect the resale value or marketability.
5. Annealing in Industry:
While annealing is a term more commonly associated with metals or other materials, it is sometimes used in the diamond industry for specific treatments to improve the visual appeal or structural integrity of the diamond. The process is not typically used to improve hardness—since diamonds are already the hardest known material—but rather to address aesthetic and internal concerns.

Summary:
Annealing diamond involves heating the diamond to high temperatures in a controlled environment to alter its colour or reduce the visibility of internal inclusions.
It is often used to enhance the colour or improve the clarity of diamonds.
The process requires careful control to avoid damaging the diamond.
Annealed diamonds should be disclosed as treated, as they may affect the value, depending on the buyer’s preferences.

If I buy a certified diamond, how do I know that the diamond in my ring is the one described on the diamond certificate or diamond grading report?

There are a number of ways to verify that your diamond matches the diamond certificate it is purchased with. If you purchased a diamond that is laser inscribed, ask your jeweller to show you the laser inscription under magnification. This way, you will always be able to identify the diamond as your own.

DCLA also performs a verification service, for both DCLA certified diamonds and for diamonds certified by other internationally recognised laboratories. Bring  or send your diamond, together with the diamond grading certificate, to the DCLA laboratory and the diamond will be conclusively matched against the certificate. DCLA can then cold laser inscribe the diamond with either the diamond grading certificate number, or with a personalised message.

How do I know that my diamond certificate or diamond grading report is from an independent laboratory ?

Ask the jeweller if the diamond certificate comes from an independent diamond laboratory or if it produced by a diamond merchant or retailer, then do your research. Make sure the certificate is issued by the DCLA or another highly respected diamond grading laboratory; DCLA is the only diamond grading laboratory worldwide to offer a full-replacement Diamond Grading Guarantee.

Lucara Sells Its 813 Carat Diamond for US$63 Million

Lucara Sells Its 813 Carat Diamond for US$63 Million, the Highest Price Ever Achieved for the Sale of a Rough Diamond.
Lucara Sells Its 813 Carat Diamond for US$63 Million, the Highest Price Ever Achieved for the Sale of a Rough Diamond.

Lucara Sells Its 813 Carat Diamond for US$63 Million, the Highest Price Ever Achieved for the Sale of a Rough Diamond.

Lucara, is pleased to announce that the exceptional 812.77 carat, Type IIa diamond recovered from the Karowe mine in Botswana in November 2015, has been sold for US$63,111,111 (US$77,649 per carat).

As part of the sale, Lucara has partnered with Nemesis International DMCC, and retains a 10% interest in the net profit received from the sale of the resultant polished diamonds.

The 813 carat diamond has been named, “The Constellation”, in collaboration with our partner. Lucara is a well-positioned diamond producer.

The Company’s main producing asset is the 100% owned Karowe Mine in Botswana.

De Beers cuts rough diamond prices and sight

De Beers which produces thirty percent of world rough diamonds has cut prices by 10 percent for the sight.

This comes after two reductions in its annual production output by 15 percent failed to slow slump in prices of rough.

Rough diamond prices have dropped 14 percent in some categories and are in their fifth consecutive quarterly loss, which is the longest in a decade.

De Beers cut the size of the sight to $250 million and reduced the prices by 9 percent, according to sight holders.  

De Beers has also contributed tens of millions to a jewellery advertising campaign. Its advertising campaign will promote diamond jewellery in the U.S. and to Chinese consumers.

Gemmological Institute of America seven week graduate diamond diploma

Gemmological Institute of America

The GIA a gemmological organisation will be conducting a seven week graduate diamond diploma from January 8.

The programme combines theory lessons with practical hands on learning and will be held in Jaipur.

Students will learn how to grade in accordance with the GIA’s 4Cs colour, cut, clarity and carat weight of diamond in the D-Z colour range.  

As well as how to grade diamonds and detect simulants and treatments like fracture filled diamonds using gemmological equipment.

The course will be taught by instructors from the Mumbai campus.

$2.1 billion in diamonds from Russia for Indian companies

Twelve Indian diamond companies including Kiran Gems, Asian Star and Rosy Blue India, have signed three year contracts with ALROSA at the World Diamond Conference,

Each of the companies signed separate contracts with ALROSA and will buy rough diamonds worth USD 2.1 billion or about USD 700 million per year for a period of three years. This will assist the companies save considerable amount of commissions.

THE INTERNATIONAL INSTITUTE OF DIAMOND GRADING

The International Institute of Diamond Grading & Research is part of the
De Beers group of companies.

Based in Antwerp and run by the world’s top diamond experts, the International Institute of Diamond Grading & Research benefits from proprietary equipment of the De Beers group of companies that enables the most precise grading and assessment for both rough and polished diamonds

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