Diamond Mining – Page 41 – The Diamond Certification Laboratory of Australia (DCLA)

Rough Trade Cautious at $455M De Beers Sale

Dealers reported a difficult but stable rough market as De Beers’ November sight closed with a value of $455 million — 4% lower than the same period a year ago.

The rough market improved slightly from the October sight, which was the smallest sale of the year as Indian manufacturing slowed for Diwali. However, sightholders still noted weak profitability on De Beers goods during November, with premiums on the secondary market close to zero.

Most boxes of diamonds from last week’s sight commanded prices on the dealer market that did not cover the costs of doing deals, explained Dudu Harari of diamond broker Bluedax in a report on the sight.

$33.8 Million For The 163 Carat Flawless Diamond At Geneva Auction

163ct De Grisogono Emerald Shape Diamond

The largest diamond offered at an auction went under the hammer in Geneva Tuesday setting a world record for a diamond of its shape.

The D colour 11A type flawless diamond was Polished from a 404 carat rough diamond which was recovered in February 2016 in the Lulo mine in Angola.

The 163.41 carat called The Art of Grisogono, sold for $33.8 million, after taxes and commissions, at the Christie’s autumn jewellery auction.

Three large diamonds Recovered at Jubilee Pipe

Alrosa the Russian miner and top diamond producer by output, recovered three gem quality large rough diamonds.

A 82.82 carat, a 108.34 carat, and a 163.11 carat all light yellow or yellow.

All three rough diamonds were recovered at the Jubilee kimberlite pipe, one of Alrosa’s Mining units Aikhalsky in the country’s northeast.

The three diamonds will be sent to Alrosa’s for assessment in the coming days.

De Beers Will Close Four Namibian Diamond Mines

Due to resources dwindling Beers’ joint ventures will close four diamond mines by 2022.

Namdeb is a DeBeers project with the government of Namibia, Will close the Elizabeth Bay mine at the end of 2018 followed by the Daberas deposit at the end of 2019 and Sendelingsdrif in 2020. The main asset Southern Coastal will close in 2022.

Production saw a shift to offshore assets this past year. For the first nine months of 2017, Debmarine’s production surged 22% to 1.1 million carats.

Subdued world economic growth will make the next few years challenging, mainly due to negative impacts forecast in exchange rates and other indices.

De Beers’ $370M Sight Reflects Slow Rough Market

De Beers’ October sight closed with a value of $370 million as rough-diamond buying slowed due to holidays and sightholders reported a sluggish dealer market.

Proceeds from the miner’s eighth sales cycle fell 27% from $507 million in the previous sight in August, and dropped 25% compared with the equivalent period a year ago, according to Rapaport records. Rough prices were largely unchanged from the previous sight, sightholders noted, with many dealers on the secondary market struggling to make a profit on the goods or even cover costs.

De Beers offered fewer rough diamonds for sale during the month as last week’s sight occurred during a period when polishing factories in India and Israel were closed for religious holidays, the company’s CEO Bruce Cleaver explained Tuesday.

“Sales were in line with expectations, at what is a seasonally slower time for rough-diamond demand,” Cleaver added.

The Indian cutting industry is preparing to close for Diwali, which occurs this Thursday. Buyers brought rough purchases forward to the July sales cycle because of the relatively early date of the festival this year, De Beers noted at previous sights. The last two sights have both been significantly smaller than a year ago as a result.

Sightholders were optimistic about the end-of-year holiday season, even as De Beers’ rough sales have declined 7% to $4.38 billion for the year to date, Rapaport records show. Russian miner Alrosa echoed this positive outlook, also noting that the timing of Diwali had weakened sales in September.

“We expect the traditional revival of the market situation in the fourth quarter, as the industry starts to prepare for the winter holiday season,” Alrosa vice president Yury Okoyomov said last week.

Source: diamonds.net

Rapaport to Auction Historic Sierra Leone 709ct. Peace Diamond

Rapaport Group has been appointed as the marketing and sales agent of the Peace Diamond by The Government of Sierra Leone.

The 709 carat Rough Diamond was recovered by diamond diggers in the village of Koryardu in Sierra Leone West Africa.

50% of the Peace Diamond sale value will directly go to benefit the community where the diamond was discovered, and the people of Sierra Leone.

37 carat Pink Diamond Up for Sale

Sotheby’s Auctioneers announced the upcoming auction of the Raj Pink diamond.

Weighing 37.30 carats the Pink diamond is the largest Fancy Intense Pink Diamond, according to Sotheby’s.

The Pink Diamond will feature at the auction house’s Magnificent Jewels in Geneva next month, and is estimated to fetch $20 million to $30 million USD.

The Original Rough Diamond was studied for over a year before the master cutter finished the polished Raj Pink Modified Cushion Brilliant cut

July, 2017February, 2025

Yellow Diamond

A yellow diamond is a coloured diamond characterised by its natural yellow body colour. Yellow must be the predominant colour in the diamond, though it can be modified by other hues, such as green, orange, or brown, which can influence the overall appearance of the stone.

Key Characteristics of Yellow Diamonds
Colour Origin:

The yellow colour in diamonds is primarily caused by the presence of nitrogen atoms within the diamond’s crystal structure. These nitrogen atoms absorb blue light, which results in a yellowish hue. The more nitrogen present, the more intense the yellow colour can become.
This unique characteristic makes yellow diamonds distinct from other coloured diamonds, such as blue diamonds, which gain their colour from the presence of boron.
Colour Variations:

While yellow diamonds are often uniformly yellow, the shade and intensity of the yellow can vary widely. Some may show a subtle, faint yellow, while others exhibit a vibrant, rich yellow that is striking and eye-catching.
The yellow can sometimes be modified by secondary hues. For instance, greenish-yellow diamonds might show a yellow-green tinge, while brownish-yellow diamonds can appear more earthy or muted. These variations in colour can affect the diamond’s overall value and appeal.
Canary Diamonds:

The term “canary diamond” refers to a particularly vivid, intense yellow diamond. These diamonds are much rarer than the more common yellow diamonds, and their colour can range from brilliant lemon yellow to golden hues.
Canary diamonds are highly prized in the market for their bright, vibrant appearance and often fetch higher prices due to their rarity and striking colour.
Rarity and Availability:

Natural yellow diamonds are relatively common compared to some other coloured diamonds, like pink or blue diamonds. However, the intensity and depth of the yellow colour can influence the rarity and desirability of a diamond.
Yellow diamonds are found in several regions around the world, including Africa, Australia, and South America.
Grading Yellow Diamonds:

Like all diamonds, yellow diamonds are graded on a combination of colour, clarity, cut, and carat weight. However, when grading coloured diamonds, the hue, tone, and saturation are the primary focus.
Hue refers to the primary colour of the diamond (in this case, yellow), tone refers to the lightness or darkness of the colour, and saturation measures the intensity of the colour. A high saturation, deep yellow diamond will generally be more valuable than a pale or less saturated one.
The most sought-after yellow diamonds have a vivid yellow hue with high saturation and a pleasing, even colour distribution throughout the stone.
Symbolism and Use:

Yellow diamonds are often associated with happiness, wealth, and success due to their vibrant, sunny appearance. They can also symbolise optimism and joy, making them a popular choice for engagement rings, jewellery, and special gifts.
Due to their striking appearance, yellow diamonds are often used in high-end jewellery, where their bold colour can stand out and create a dramatic effect.
Price and Market Appeal:

The price of yellow diamonds can vary significantly depending on factors like colour intensity, clarity, and size. Vivid yellow diamonds, particularly those with a deep, rich hue, tend to fetch higher prices due to their rarity and the high demand in the luxury market.
However, the relative abundance of yellow diamonds compared to other coloured diamonds like pink or blue means they are often more affordable than rarer varieties.

Yellow diamonds are a beautiful and unique variety of coloured diamonds, with their colour arising from the presence of nitrogen in their crystal structure. While yellow diamonds are relatively common, those with intense yellow hues, such as canary diamonds, are rarer and more valuable. These diamonds are graded based on their hue, tone, and saturation, and are prized for their vivid and radiant appearance. They are a popular choice in fine jewellery, symbolising happiness, wealth, and success, while also offering an affordable yet striking alternative to more expensive coloured diamonds.

July, 2017February, 2025

Table

The table is one of the most important facets of a polished diamond, situated at the very top of the diamond, in the crown area. It is the largest flat facet on the diamond and plays a crucial role in how light interacts with the stone. The table facet is typically positioned parallel to the girdle, which is the outermost edge of the diamond, and it serves as a window through which light enters and exits the diamond. The size and proportion of the table facet significantly impact the overall appearance, brilliance, and sparkle of the diamond.

Position and Shape:
The table is flat and circular in shape, with its size and dimensions typically defined as a percentage of the diameter of the diamond, measured from the girdle.
It is placed directly at the top of the diamond, centered on the crown. For round brilliant cut diamonds, the table should be symmetrical to allow for even light reflection and maximum brilliance.
The size of the table relative to the overall dimensions of the diamond is an important factor in its overall cut quality and light performance. A table that is too large or too small can negatively affect the diamond’s visual appeal.
Role of the Table in Diamond Brilliance:
The table facet is the primary surface through which light enters the diamond, and its quality directly influences the diamond’s brilliance (the amount of white light reflected). Light entering the table facet is refracted through the diamond’s other facets, creating the sparkle and life that is characteristic of a well-cut diamond.
If the table is too large, it may result in excessive light leakage, where light passes through the bottom of the diamond, reducing its brilliance. Conversely, a table that is too small may limit the diamond’s ability to reflect light effectively, making the diamond appear darker or less vibrant.
Table and Diamond Cut Quality:
The size of the table is one of the key factors considered when assessing a diamond’s cut grade. The table-to-depth ratio is calculated by measuring the table’s diameter and comparing it to the diamond’s overall depth. An ideal round brilliant cut diamond typically has a table size that falls within a certain percentage range of its overall diameter, usually between 53% and 58% for optimal brilliance.

Ideal Table Size: For round brilliant cut diamonds, an ideal table size typically falls between 53% and 58% of the overall diameter, balancing light reflection and maximizing brilliance.
Large Table: A diamond with an excessively large table relative to its depth may reflect less light, leading to a loss of brilliance and a flat appearance. In contrast, a smaller table could result in a diamond that looks darker or less reflective.
Table in Fancy Shapes:
While the table is a key feature in all diamonds, it is especially important for round brilliant cut diamonds. In fancy-shaped diamonds, such as princess, emerald, and asscher cuts, the table may vary slightly in shape and size to accommodate the unique proportions and angles of each cut. However, the role of the table in influencing light entry and brilliance remains consistent across all diamond shapes.

DCLA and Table Quality:
The Diamond Certification Laboratory of Australia (DCLA) is one of the leading authorities in diamond grading and certification, particularly within the Australian market. When a diamond is graded by DCLA, the table is assessed as part of the overall cut grade. DCLA uses a comprehensive set of criteria to evaluate all facets of the diamond, including the table facet.

The table is evaluated for size, symmetry, and alignment, ensuring that it contributes to the overall quality of the cut and the diamond’s ability to reflect light properly.
DCLA reports provide detailed information about the table size in relation to the diamond’s total diameter, helping consumers and investors understand how the table contributes to the diamond’s brilliance and overall visual appeal.
DCLA also measures the proportions of the table and other facets, ensuring that the diamond meets industry standards for ideal proportions. The laboratory’s expertise in evaluating the table facet, alongside other critical attributes like crown angle and pavilion depth, ensures that each diamond receives a thorough and accurate grading report that reflects its true quality.

Table and Diamond Certification:
In the grading report issued by DCLA, the table facet is one of the important details that helps determine the diamond’s overall cut grade. Since the cut is a significant factor in determining the diamond’s beauty and value, the size, proportions, and finish of the table are carefully examined. A well-proportioned table enhances the diamond’s light performance, while an incorrect or poorly finished table can result in suboptimal visual appeal.

In addition to the table’s size, the report may also include additional information about the table’s polish, symmetry, and overall surface quality, as these factors all influence the diamond’s final appearance.

The table is a crucial facet in determining a diamond’s overall beauty and brilliance. Its size, shape, and position play a vital role in how the diamond interacts with light and contributes to the diamond’s overall sparkle and visual appeal. Whether it is a round brilliant cut diamond or a fancy shape, the quality and proportions of the table can significantly affect the diamond’s grade and value. The DCLA ensures that diamonds are thoroughly assessed and accurately graded, with special attention to the table’s impact on the diamond’s overall cut quality and performance.

July, 2017February, 2025

Rough Diamond

A rough diamond is a diamond in its natural state, exactly as it is found deep within the Earth. It has not yet undergone any form of cutting, polishing, or alteration. Rough diamonds are typically irregular in shape, with a variety of textures, colours, and surface conditions, ranging from clear and transparent to opaque and coloured.

These diamonds are generally discovered in kimberlite pipes (volcanic formations) or alluvial deposits (water-worn areas), and they are extracted through a process of mining. Once found, rough diamonds are carefully sorted and graded based on their size, shape, colour, and clarity before they are sent to gem cutters for transformation into polished stones.

Key Characteristics of Rough Diamonds
Shape:

Rough diamonds are typically irregular, with shapes that can range from octahedral (two pyramidal shapes joined together) to dodecahedral (a 12-sided form). These shapes are determined by the crystal structure of the diamond and can vary widely.
The rough shape is not intended for jewellery, and the gem cutters will plan how to cut the stone based on its natural geometry to maximise yield and minimise waste.
Colour:

Rough diamonds can appear in a wide range of colours, from colourless and transparent to shades of yellow, brown, or even rare colours such as blue, green, or pink.
The final colour of the diamond will depend on its internal structure and any trace elements present in the rough material. Some rough diamonds are even tinted due to the presence of minerals or impurities.
Clarity:

In their natural form, rough diamonds may have a variety of inclusions and blemishes, such as tiny air bubbles or mineral inclusions trapped within the crystal. These internal flaws are often visible to the naked eye or under magnification, though they can be reduced or eliminated during the cutting and polishing processes.
Size:

Rough diamonds vary greatly in size, from small pebbles to large stones weighing several carats. Larger rough diamonds are often considered more valuable, especially if they possess good colour and clarity, as they can be cut into high-quality finished diamonds.
The Journey of a Rough Diamond
Extraction:

Rough diamonds are mined from the Earth, typically through open-pit mining, underground mining, or alluvial mining (searching for diamonds in riverbeds or coastal regions). Mining companies extract the rough stones from kimberlite pipes or riverbeds, often using advanced technology to locate diamond deposits deep underground.
Sorting and Grading:

Once extracted, rough diamonds are sorted based on their size, colour, clarity, and shape. Each diamond is examined to determine its potential for cutting and polishing. Some rough diamonds are too flawed or small to be cut into gem-quality stones and may be used for industrial purposes instead.
The DCLA (Diamond Certification Laboratory of Australia) offers rough diamond services to help classify and grade rough diamonds. They use their expertise to evaluate the quality of rough diamonds and assist in planning the best course of action for cutting and polishing.
Cutting and Polishing:

After sorting, the rough diamond is sent to skilled gem cutters, who use advanced techniques and tools to transform the stone into its finished form. The cutting process involves careful planning to maximise the yield (the amount of diamond produced from the rough stone) while aiming to enhance the diamond’s brilliance, fire, and overall appearance.
The diamond may be cut into a variety of shapes, such as round, emerald, princess, or cushion, depending on the rough stone’s shape and quality.
Grading:

Once the diamond is cut and polished, it is then graded according to the 4 Cs – Carat, Colour, Clarity, and Cut. This grade determines the diamond’s final value, and certificates from recognised laboratories such as DCLA are used to authenticate the quality of the diamond.
Uses of Rough Diamonds
Gem-quality Diamonds:

The primary use of rough diamonds is for gemstone production, where they are cut and polished into diamonds for use in engagement rings, earrings, necklaces, and other high-end jewellery.
Industrial Diamonds:

Some rough diamonds, particularly those with significant imperfections, are not suitable for use in jewellery. These diamonds are used for industrial purposes, where their hardness is highly valued. Industrial diamonds are employed in applications such as cutting, grinding, drilling, and polishing, where the diamond’s extreme hardness makes it ideal for cutting or shaping other materials.

The rough diamond is the very first step in the life cycle of a diamond. Found in the earth in its natural form, it is then extracted, sorted, and carefully crafted into the sparkling gemstones that are valued in fine jewellery. Due to their rarity and the complexity of their transformation, rough diamonds represent both the mystery of nature and the skill of the craftsmen who shape them into stunning finished products.