DIAMON GRADING
The 4 C’s | Diamonds are graded by four characteristics known as the 4 C’s
Carat Diamond and most other gem weights are expressed in metric carats. One carat equals 0.2g or 1/5 of a gram and is divided into 100 equal units called points.
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Colour Diamonds are found in a variety of tints and are graded according to their inner body hue on a colour scale that ranges from D being completely colourless through to Z which is strong yellow.
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If a diamond’s colour differs from the D to Z colour range, then it is known as a Fancy Colour which is graded according to its intensity. Grading fancy coloured diamonds is complex and specialized, and done by highly trained laboratory graders.
The rarest and most valuable fancy colours are saturated pinks, blues, and greens. Fancy yellows, sometimes referred to as “canary”, and browns, which are known as either ‘cognac” or “champagne”, are more readily available as are black diamonds.
Fancy colours can be enhanced by irradiation and heat treatment. This treatment needs to be declared and the diamond is then referred to as a ‘treated colour’ or ‘enhanced colour’ diamond.
Clarity Almost all natural diamonds contain identifying characteristics, known as inclusions. Many of these blemishes are not visible to the unaided eye, yet they are unique to the stone and form the diamond’s own fingerprint, making your diamond truly individual.
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Cut As the only characteristic that is governed by the hand of a skilled craftsman, the true beauty of a diamond depends on the way that its cut allows it to reflect and refract light. A well-cut diamond, regardless of its shape, colour and clarity, scintillates with fire and light – unleashing brilliance and beauty!
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Diamond jewellery Diamond engagement rings or diamond wedding rings use polished diamonds that are set into precious metals. When a diamond is found in its natural state, it is referred to as a ‘rough’ diamond. Once facetted a cut diamond, whether to be set in diamond jewellery or sold loose, it can be certified and graded according to the four characteristics namely carat, colour, clarity and cut. Diamonds can also be sold uncertified which is often the case with smaller sizes.
Petra Jewellery Design™ has many years of experience working with diamonds. Diamond engagement rings and diamond-set wedding rings are some of our most popular jewellery items for design and manufacture. Our clients are able to choose from a range of stones to suit their individual requirements and preferences and our diamond jewellery is always issued with a detailed valuation certificate. Petra Jewellery Design™ will source diamonds upon request and is available for consultation and advice regarding diamonds and other precious stones.
TANZANITE GRADING 1
Tanzanite jewellery has become some of the most desired jewellery in the world. Tanzanite rings, earrings and necklaces featuring these tantalizing gemstones are extremely fashionable, and absolutely adored by those who own them!
HISTORY & ORIGIN
Tanzanite was discovered in 1967 and named after its country of origin. The popularity of Tanzanite is global, yet it is found in only one location in the world: The Merelani Hills of Tanzania, resting in the shadow of Mount Kilimanjaro.
Tanzanite is said to be one thousand times rarer than diamonds and to be the colour “that a sapphire would love to be”. Tanzanite is a precious gift from the dark depths of the earth – an irresistible gemstone with a stylish future.
TANZANITE GRADING
Tanzanite jewellery is created with gemstones that have been cut, polished, and graded. Larger gemstones used in Tanzanite rings, earrings and necklaces undergo grading for a Tanzanite Report or Certificate. Just as diamonds are submitted for diamond grading, this involves assessing the nature of the stone, the carat weight, dimensions and shape, colour hue and saturation, as well as the clarity and finish of each stone.
COLOUR Tanzanite is trichroic, which means that it displays 3 different colours when viewed from different directions. These colours are blue, violet and bronze or red. When Tanzanite is found in the ground, the bronze colour dominates.
Gentle heating enhances the colour that already exists within the stone, changing the brownish-red shades to Tanzanite’s distinctive blue-violet colour. Heat treatment cannot create colour and it will not improve the quality of the stone.
Tanzanite can show a dominance of either Blue or Violet or a combination thereof, this is referred to as the colour hue. There are five categories of saturation, indicating the strength or intensity of the colour, VIVID being the strongest colour on the grading scale and PALE is the weakest.
|
Colour Hue |
Saturation |
Colour Hue |
|
Blue – VIOLET |
VIVID |
Violet – BLUE |
|
Blue – VIOLET |
INTENSE |
Violet – BLUE |
|
Blue – VIOLET |
MODERATE |
Violet – BLUE |
|
Blue – VIOLET |
LIGHT |
Violet – BLUE |
|
Blue – VIOLET |
PALE |
Violet – BLUE |
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CLARITY refers to the natural inclusions within the gemstone.
|
LC |
Loupe Clean |
|
EC |
Eye Clean |
|
LI |
Lightly Included |
|
MI |
Moderately Included |
|
HI |
Heavily Included |
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CUT & FINISH refers to the shape, facet pattern and proportions of the Tanzanite.
A well-cut gemstone will reflect light back from within itself creating the brilliance and colour play that makes Tanzanite jewellery so unique and desirable. Tanzanite is fashioned in various styles and shapes such as round, oval, square, or rectangular cushion, princess, trilliant, heart, octagon, and pear shape.
The final polish, symmetry and external characteristics are graded as finish:
|
A |
Excellent |
|
B |
Very Good |
|
C |
Good |
|
D |
Fair |
|
E |
Poor |
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CARAT Tanzanite’s weight is measured in carats.
As a Tanzanite increases in carat weight, so will the visibility of colour and possible inclusions, although a larger weight does not guarantee a better colour and quality. There are no fixed cutting proportions governing Tanzanite and two seemingly identical stones can have different carat weights if their depth varies.
TANZANITE JEWELLERY should be treated gently and with care.
Tanzanite is a softer gemstone and wear during rigorous activity is best avoided – for rings this includes gardening and washing dishes. To minimise the risk of damage to your Tanzanite when set in a ring, selective wear, as opposed to everyday wear, is recommended.
Petra Jewellery Design™ offers sourcing of gemstones, jewellery design and manufacturing services in gold, palladium, and platinum, and can assist with diamond grading and Tanzanite grading.
Contact Petra Jewellery Design™ for more information.
TANZANITE GRADING 2
Tanzanite jewellery has become some of the most desired jewellery in the world. Tanzanite rings, earrings and necklaces featuring these tantalizing gemstonesare extremely fashionable, and absolutely adored by those who own them!
Tanzanite was discovered in 1967 and named after its country of origin. The popularity of Tanzanite is global, yet it is found in only one location in the world: The Merelani Hills of Tanzania, resting in the shadow of Mount Kilimanjaro.
Tanzanite is said to be one thousand times rarer than diamonds and to be the colour “that a sapphire would love to be”. Tanzanite is a precious gift from the dark depths of the earth – an irresistible stone with a stylish future.
Tanzanite jewellery is created with stones which have been cut, polished and graded. The gemstones in Tanzanite rings, earrings and necklaces undergoTanzanite grading, just as diamonds are submitted for diamond grading, which involves assessing the carat, cut, colour and clarity of each stone.
COLOUR
Tanzanite is trichroic, which means that it displays 3 different colours when viewed from different directions. These colours are blue, violet and bronze or red. When Tanzanite is found in the ground, the bronze colour dominates.
Gentle heating enhances the colour that already exists within the stone, changing the brownish-red shades to Tanzanite’s distinctive blue-violet colour. Heat treatment cannot create colour and it will not improve the quality of the stone.
Tanzanite can show a dominance of intensity of either Blue or Violet or a combination thereof. There are five categories of saturation, VIVID being the darkest colour on the grading scale and PALE being the lightest.
| Colour Hue | Saturation | Colour Hue |
| Blue-VIOLET | VIVID | Violet-BLUE |
| Blue-VIOLET | INTENSE | Violet-BLUE |
| Blue-VIOLET | MODERATE | Violet-BLUE |
| Blue-VIOLET | LIGHT | Violet-BLUE |
| Blue-VIOLET | PALE | Violet-BLUE |
CLARITY
Clarity refers to the natural inclusions within the gemstone.
| LC | Loupe Clean |
| EC | Eye Clean |
| LI | Lightly Included |
| MI | Moderately Included |
| HI | Heavily Included |
CUT
Cut refers to the shape, facet pattern and proportions of the Tanzanite. A well-cut gemstone will reflect light back from within itself creating the brilliance andcolour play that makes Tanzanite jewellery so unique and desirable. Tanzanite is fashioned in various styles and shapes such as oval, square cushion, princess, trilliant, heart, octagon, round and pear shape.
The final polish, symmetry and external characteristics are graded as finish:
| A | Excellent |
| B | Very Good |
| C | Good |
| D | Fair |
| E | Poor |
CARAT
Tanzanite’s weight is measured in carats. As a Tanzanite increases in carat, so will the visibility of colour and possible inclusions, although a larger weight does not guarantee a better quality and colour. There are no fixed cutting proportions governing Tanzanite and two seemingly identical stones can have different carat weights if their depth varies.
If you are looking for custom jewellery design from South Africa, Petra Jewellery Design offers gemstone, gold and platinum jewellery design services and can assist with diamond grading and Tanzanite grading. Contact Petra Jewellery Design™ for more information.
MOISSANITE GRADING
A Brilliant Discovery
Moissanite was first discovered in 1893 at the site of a large meteorite crater in Arizona by the Nobel Prize-winning French chemist Dr. Henri Moissan and named in his honour. The tiny particles were initially mistaken for diamonds due to their hardness and brilliant reflectiveness, but after further testing, were identified as naturally-occurring silicon carbide (SiC). Dr. Moissan spent the rest of his life attempting to re-create this exceptional mineral, which is commercially useful and among the hardest materials on earth.
Charles & Colvard
Moissanite was introduced to the jewellery market in 1998 after Charles & Colvard received patents to create and market lab-grown silicon carbide gemstones, becoming the first company to do so. Charles & Colvard currently makes and distributes moissanite gems under the trademarks Forever One, Forever Brilliant and Forever Classic.
As the original creator of moissanite they are dedicated to offering environmentally and ethically responsible gemstone choices in the fine jewellery industry. All Charles & Colvard® created gemstones are backed by a Charles & Colvard Certificate of Authenticity and Limited Lifetime Warranty.
Petra Jewellery DesignTM exclusively offers Charles & Colvard Created Moissanite and we regard moissanite as a diamond alternative, not a simulant.
Beauty Redefined
A beautiful and durable man-made gemstone, with a 9.25 hardness that rivals that of any mineral on earth, and refractive properties exceeding that of diamond.
Its lower price and less exploitative mining practices necessary to obtain it make it a popular alternative to diamonds mainly for engagement rings created in white gold, yellow gold or rose gold, palladium, and platinum. Moissanite can be used on its own or in combination with small diamonds in complementing colours. It is also an excellent choice for earrings and pendant necklaces.
Petra Jewellery DesignTM is proud to offer Charles & Colvard Created Moissanite as an alternative to those clients, who want the ‘big diamond look without the big diamond price tag’ or who have ethical conflicts with diamonds.
THE 5 C’s OF MOISSANITE
CUT Every Charles & Colvard Created Moissanite gem is precisely calibrated and hand-faceted by master gem cutters to maximize brilliance and sparkle that increases the refractive index of moissanite.
COLOUR The past two decades have seen ongoing research and development aimed at expanding the colour range of Charles & Colvard Created Moissanite to meet market demand.
The original Forever Classic™ falls into the FAINT COLOUR or J-K designation
The Forever Brilliant® is slightly whiter and NEAR-COLOURLESS in a broad selection in the G-H-I range.
The Forever One™ is an unfailingly pure white, COLOURLESS gem in the premium D-E-F range. The crowning achievement in gem innovation by Charles & Colvard.
CLARITY Moissanite’s clarity grading is “eye-clean”.
Charles & Colvard® creates moissanite using organic elements, mimicking nature in a controlled environment, therefore moissanite gems have tiny, needle-like inclusions that develop during the growing process and are not visible to the unaided eye. Only moissanite gemstones that pass Charles & Colvard’s stringent quality standards are made available for distribution.
CARAT SIZE Moissanite carat weight is approximately 12% lighter than the equivalent diamond size.
A 6.5mm round brilliant natural diamond would weigh approximately 1.00ct compared to a 6.5mm moissanite which has a weight of approximately 0.88ct. To the eye, they appear to be the same size, although the weight of the two stones is different.
For this reason, moissanite is sold by size rather than carat weight.
Like other gems, large sizes of moissanite are rare. However, the premium for large sizes is much less, making moissanite a particularly good choice for bold jewellery designs.
CONFIDENCE All Charles & Colvard® created gemstones are backed by a Charles & Colvard Certificate of Authenticity and Limited Lifetime Warranty.
Charles & Colvard® ensures that your moissanite gemstone is an original of exceptional quality & craftsmanship. Grown in an American laboratory, Charles & Colvard Created Moissanite® is a responsible alternative to mined gems, providing jobs without damaging the environment.
Charles & Colvard Created Moissanite’s durability means that its beauty and value will endure. Moissanite is one of the hardest minerals on earth and is extremely resistant to scratching, abrasion, breaking, or chipping. Charles & Colvard’s promise to you is that its fire and brilliance will last forever.
Known to many as “The World’s Most Brilliant Gem®”, with unsurpassed fire and brilliance, this unique created gemstone is the ultimate in affordable luxury.
Please visit www.moissanite.co.za for more info and prices.
EXPERTISE
Diamond Grading
Tanzanite
Moissanite
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