Rough Diamonds – Page 49 – The Diamond Certification Laboratory of Australia (DCLA)

Petra Diamonds shares drop

More trouble for diamond miner Petra Diamonds yesterday after it warned it is heading into financial trouble with its lenders.

Petra has borrowed heavily to expand its operations in the country. The company is now likely to breach its banking covenants at the end of the year, because of the row with the government in Tanzania. As well as strikes at three of its mines in South Africa.

Petra diamonds is known for the size and quality of the diamonds produced at the famous Cullinan mine outside of Pretoria in South Africa.

Young Rough Diamonds Discovered

Geologists have discovered what they refer to as young diamonds, after analyzing a number of rough diamonds.

It now appears the creation of rough diamonds, may have occurred later in the Earth’s history than was previously thought. Diamond requires extreme temperatures and pressures to form. Geologists though these conditions only existed in the early formation of Earth.

Small impurities in the diamonds could indicate the conditions in which they are formed. So 26 diamonds donated by the De Beers Group where analyzed by a research team in Amsterdam.

Sm-Nd isotope techniques are used by researchers to analyzed the sampled garnet inclusions, Which are a common mineral found in Earth’s mantle and sometimes within the diamonds.

The scientists discovered two sets of diamonds, one of Archaean age 2.95 billion years old thought to be the original source of the diamonds. And then surprisingly the other of Proterozoic age 1.15 billion years old.

Botswana Wants Option to Buy Unusually Big Diamonds

The world’s second largest 1,109 carat rough diamond discovered two years ago, has prompted the Botswana government to amend the law giving it first option to buy unusually large diamonds.

Botswana’s success has been due to the rough diamond mines.

An official told a local newspaper that it referred to stones that were unusually large, were particularly clear or had a rare colour.

The price will agreed between the government and the producer, both parties with the current market price of the rough stones.

Petra Diamonds suspends operations at its Tanzania mine

The Tanzanian governments confrontational approach to miners operating in the country including Petra Diamonds, has led to Petra suspending operations at its mine.

The Tanzanian government seized a shipment of rough diamonds belonging to Petra. They also question and held a number of staff in the latest assault on the African country’s mining sector.

This includes the concentrate exports ban and the non repayment of value added tax.

Diamond stockpiles Increase In Indian Companies

A US slowdown in demand for polished diamonds is gradually building up inventories at Indian jewellery manufacturing companies, leading to a decline in diamond prices by as much as seven percent this month.

The US usually orders bulk for the holiday season, but this year the volumes are down.

Inventories have started piling up at the manufacturing units. It will become a matter of worry if this continues for long. We do not expect manufacturing activities to be cut down due to this slowdown in export markets. Manufacturing companies may reduce rough purchases.

Diamond markets in Belgium and Israel are also quiet. Rough diamond trading has slowed.

De Beers Raises Marketing Budget to USD $140M

De Beers marketing spend this years is more than $140 million, This is the biggest De Beers push in a decade.

The marketing will focus on increasing consumer demand for diamond jewellery in US, China and Indian markets.

The De Beers brands, Forevermark and De Beers Diamond Jewellers. Will receive the most funding, But Debeers will also increase its contributions to the Diamond Producers Association and India’s Gem & Jewellery Export Promotion Council.

Stephen Lussier, De Beers’ executive vice president of marketing and CEO of Forevermark. Said the consumer expenditure for diamond jewellery over the past five years collectively has been the highest on record. and this made the outlook positive.

Seven Diamonds Over 50 Carats Recovered By Lucapa

Lucapa Diamond Company announced Thursday it has recovered seven stones exceeding 50 carats at its Lulo mine in Angola, including two type IIa stones.

The two IIa stones weigh 68 carats and 83 carats. All seven rough diamonds scheduled to sell in September as part of the next parcel marketed by Sociedade Mineira Do Lulo the mining company in which Lucapa has a 40% stake.

The large diamond finds come from Lulo’s block 8, at which Lucapa recently resumed operations at the end of the wet season.

This area is known for yielding large diamonds, including Angola’s 404 carat rough diamond which is the biggest recorded and sold for $16 million.

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.

July, 2017February, 2025

Pinpoints

Pinpoints are extremely small diamond crystal inclusions that are typically too tiny to distinguish their individual shapes, even under magnification. When viewed under 10x magnification, a single pinpoint appears as a minute, white or black “dot” within the diamond. While a single pinpoint is often insignificant and may not affect a diamond’s overall clarity or brilliance, multiple pinpoints grouped together can form a cloud—a hazy or milky area within the diamond that can impact its transparency and light performance.

These inclusions are a natural part of a diamond’s formation process and are commonly found in many diamonds. Depending on their number, size, and location, pinpoints can have varying effects on a diamond’s clarity grade. In some cases, when they are sparsely distributed, they have little to no visible impact. However, if they are densely clustered, forming a significant cloud, they may lower the diamond’s clarity rating and slightly reduce its brilliance by affecting how light passes through the stone.

Pinpoints are one of the many inclusions that gemologists assess when grading diamonds, and they are often documented on a diamond’s grading report issued by reputable gemological laboratories such as the GIA (Gemological Institute of America) or DCLA (Diamond Certification Laboratory of Australia).