Diamond Information

London Diamonds - Hirschfelds Diamonds Hatton Garden London EC1

Hirschfelds Diamonds have been in the heart of London's jewellery trade Hatton Garden London since 1875.
Our skilled London goldsmiths are experienced craftsmen who can create your dream Diamond Ring in our Hatton Garden jewellery workshop London.

Please call for an appointment to view loose diamonds, Old Cut Diamond rings, Diamond Rings, Diamond earrings and Diamond Pendants in our London Hatton Garden Offices and workshop.

DIAMONDS may be an investors best friend - as well as a girl's!

Diamond has held pride of place as chief of precious stones ever since the discovery of the form of cutting known as the "Brilliant".

The Brilliant revealed to full perfection its amazing qualities; and justly so, since it combines in itself extreme hardness, high refraction, large colour dispersion and brilliant lustre.

Diamond Carat weight

The carat weight measures the mass of a diamond. One carat is defined as 200 milligrams (about 0.007 ounce avoirdupois). The point unit—equal to one one-hundredth of a carat (0.01 carat, or 2 mg)—is commonly used for diamonds of less than one carat. All else being equal, the price per carat increases with carat weight, since larger diamonds are both rarer and more desirable for use as gemstones.

The price per carat does not increase smoothly with increasing size. Instead, there are sharp jumps around milestone carat weights, as demand is much higher for diamonds weighing just more than a milestone than for those weighing just less. As an example, a 0.95 carat diamond may have a significantly lower price per carat than a comparable 1.05 carat diamond, because of differences in demand.

A diamond's size is measured in carat weight. The larger a diamond, the more rare it is.

Each carat is equal to 100 points.
A .75 carat diamond is the same as a 75-point diamond or a 3/4 carat stone.
Diamonds of equal size may vary widely in value and brilliance, depending on their qualities of clarity, cut, and colour.

Diamond Clarity
Virtually all natural diamonds contain identifying characteristics, yet many are invisible to the naked eye. Under the scrutiny of a jeweller's 10x-magnifying loupe or microscope, natural phenomena -- called inclusions -- may be seen. These are nature's birthmarks, and they may look like tiny crystals, clouds, or feathers. The number, colour, type, size and position of surface and internal inclusions affect a diamond's value.
Diamonds categorized as internally flawless reveal no such inclusions.Flawless stones are treasured for their rarity and beauty.Diamonds with very, very small inclusions are graded as VVS1 or VVS2. The larger the inclusion, the lower the grade and the less rare the diamond. Inclusions that can be seen with the naked eye are graded I1, I2 or I3. Major inclusions can interfere with the path of light that travels through a diamond, diminishing its brilliance and sparkle and therefore its value.
Clarity is a measure of internal defects of a diamond called inclusions. Inclusions may be crystals of a foreign material or another diamond crystal, or structural imperfections such as tiny cracks that can appear whitish or cloudy. The number, size, colour, relative location, orientation, and visibility of inclusions can all affect the relative clarity of a diamond. The Gemological Institute of America (GIA) and other organizations have developed systems to grade clarity, which are based on those inclusions which are visible to a trained professional when a diamond is viewed under 10x magnification.

Diamonds become increasingly rare when considering higher clarity gradings. Only about 20 percent of all diamonds mined have a clarity rating high enough for the diamond to be considered appropriate for use as a gemstone; the other 80 percent are relegated to industrial use. Of that top 20 percent, a significant portion contains one or more visible inclusions. Those that do not have a visible inclusion are known as "eye-clean" and are preferred by most buyers, although visible inclusions can sometimes be hidden under the setting in a piece of jewelry. Most inclusions present in gem-quality diamonds do not affect the diamonds' performance or structural integrity. However, large clouds can affect a diamond's ability to transmit and scatter light. Large cracks close to or breaking the surface may reduce a diamond's resistance to fracture.

Diamonds are graded by the major societies on a scale ranging from flawless to imperfect

Diamonds with higher clarity grades are more valued, with the exceedingly rare "flawless" graded diamond fetching the highest price. Minor inclusions or blemishes are useful, as they can be used as unique identifying marks analogous to fingerprints. In addition, as synthetic diamond technology improves and distinguishing between natural and synthetic diamonds becomes more difficult, inclusions or blemishes can be used as proof of natural origin

Diamond Colour
Click here to discover interesting "D" Colour Diamond information.
The purer a diamond's colour, the rarer it is. Diamonds are graded by colour, starting at D and continuing through the alphabet. While many diamonds appear colourless, they may actually have subtle yellow or brown tones. Although still beautiful, they will be less rare and therefore less valuable.
To appreciate the simple beauty of each individual stone, you should compare diamonds side by side with a jeweller.
"Fancy" diamonds -- in well defined colours that include red, pink, blue, green and canary yellow -- are highly prized and particularly rare.

A chemically pure and structurally perfect diamond is perfectly transparent with no hue, or colour. However, in reality almost no gem-sized natural diamonds are absolutely perfect. The coolur of a diamond may be affected by chemical impurities and/or structural defects in the crystal lattice. Depending on the hue and intensity of a diamond's coloration, a diamond's colour can either detract from or enhance its value. For example, most white diamonds are discounted in price as more yellow hue is detectable, while intense pink or blue diamonds (such as the Hope Diamond) can be dramatically more valuable.

Most diamonds used as gemstones are basically transparent with little tint, or white diamonds. The most common impurity, nitrogen, replaces a small proportion of carbon atoms in a diamond's structure and causes a yellowish to brownish tint. This effect is present in almost all white diamonds; in only the rarest diamonds is the coloration from this effect undetectable. The GIA has developed a rating system for color in white diamonds, from "D" to "Z" (with D being "colourless" and Z having a bright yellow coloration), which has been widely adopted in the industry and is universally recognized, superseding several older systems once used in different countries. The GIA system uses a benchmark set of natural diamonds of known colour grade, along with standardized and carefully controlled lighting conditions. Diamonds with higher colour grades are rarer, in higher demand, and therefore more expensive, than lower colour grades. Oddly enough, diamonds graded Z are also rare, and the bright yellow colour is also highly valued. Diamonds graded D-F are considered "colourless", G-J are considered "near-colourless", K-M are "slightly coloured". N-Y usually appear light yellow or brown.

In contrast to yellow or brown hues, diamonds of other colours are more rare and valuable. While even a pale pink or blue hue may increase the value of a diamond, more intense colouration is usually considered more desirable and commands the highest prices. A variety of impurities and structural imperfections cause different colous in diamonds, including yellow, pink, blue, red, green, brown, and other hues. Diamonds with unusual or intense colouration are sometimes labeled "fancy" by the diamond industry. Intense yellow colouration is considered one of the fancy colours, and is separate from the colour grades of white diamonds. Gemmologists have developed rating systems for fancy coloured diamonds, but they are not in common use because of the relative rarity of coloured diamonds.

Diamonds occur in a restricted variety of colours — steel gray, white, blue, yellow, orange, red, green, pink to purple, brown, and black. Coloured diamonds contain interstitial impurities or structural defects that cause the coloration, whilst pure diamonds are perfectly transparent and colorless. Diamonds are scientifically classed into two main types and several subtypes, according to the nature of impurities present and how these impurities affect light absorption:

Type I diamond has nitrogen (N) atoms as the main impurity, commonly at a concentration of 0.1 percent. If the N atoms are in pairs they do not affect the diamond's color; these are Type IaA. If the N atoms are in large even-numbered aggregates they impart a yellow to brown tint (Type IaB). About 98% of gem diamonds are type Ia, and most of these are a mixture of IaA and IaB material: these diamonds belong to the Cape series, named after the diamond-rich region formerly known as Cape Province in South Africa, whose deposits are largely Type Ia. If the N atoms are dispersed throughout the crystal in isolated sites (not paired or grouped), they give the stone an intense yellow or occasionally brown tint (Type Ib); the rare canary diamonds belong to this type, which represents only 0.1 percent of known natural diamonds. Synthetic diamond containing nitrogen is Type Ib. Type I diamonds absorb in both the infrared and ultraviolet region, from 320 nm. They also have a characteristic fluorescence and visible absorption spectrum (see Optical properties of diamond).

Type II diamonds have very few if any nitrogen impurities. Type IIa diamond can be coloured pink, red, or brown due to structural anomalies arising through plastic deformation during crystal growth—these diamonds are rare (1.8 percent of gem diamonds), but constitute a large percentage of Australian production. Type IIb diamonds, which account for 0.1 percent of gem diamonds, are usually a steely blue or grey due to scattered boron within the crystal matrix; these diamonds are also semiconductors, unlike other diamond types (see Electrical properties of diamond). However, an overabundance of hydrogen can also impart a blue colour; these are not necessarily Type IIb. Type II diamonds absorb in a different region of the infrared, and transmit in the ultraviolet below 225 nm, unlike Type I diamonds. They also have differing fluorescence characteristics, but no discernible visible absorption spectrum.

Diamond Cut

A well cut or faceted diamond, regardless of its shape, scintillates with fire and light -- offering the greatest brilliance and value. While nature determines a diamond's clarity, carat weight and colour, the hand of a master craftsman is necessary to release its fire, sparkle and beauty. When a diamond is cut to good proportions, light will reflect from one mirror-like facet to another and disperse through the top of the stone, resulting in a display of brilliance and fire. Diamonds that are cut too deep or too shallow lose light that spills through the side or bottom. As a result, poorly cut stones will be less brilliant and beautiful -- and certainly less valuable -- than well cut diamonds.
Diamond cutting is the art and science of creating a gem-quality diamond out of mined rough. The cut of a diamond describes the manner in which a diamond has been shaped and polished from its beginning form as a rough stone to its final gem proportions. The cut of a diamond describes the quality of workmanship and the angles to which a diamond is cut. Often diamond cut is confused with "shape".

There are mathematical guidelines for the angles and length ratios at which the diamond is supposed to be cut in order to reflect the maximum amount of light. Round brilliant diamonds, the most common, are guided by these specific guidelines, though fancy cut stones are not able to be as accurately guided by mathematical specifics.

The techniques for cutting diamonds have been developed over hundreds of years, with perhaps the greatest achievements made in 1919 by mathematician and gem enthusiast Marcel Tolkowsky. He developed the round brilliant cut by calculating the ideal shape to return and scatter light when a diamond is viewed from above. The modern round brilliant has 57 facets (polished faces), counting 33 on the crown (the top half), and 24 on the pavilion (the lower half). The girdle is the thin middle part. The function of the crown is to diffuse light into various colors and the pavilion's function to reflect light back through the top of the diamond.

Tolkowsky defines the ideal dimensions to have:

Table percentage (table diameter divided by overall diameter)=53%
Depth percentage (Overall depth divided by the overall diameter)=59.3%
Pavilion Angle (Angle between the girdle and the pavilion)=40.75°
Crown Angle (Angle between the girdle and the crown)=34.5°
Pavilion Depth (Depth of pavilion divided by overall diameter)=43.1%
Crown Depth (Depth of crown divided by crown diameter)=16.2%
The culet is the tiny point or facet at the bottom of the diamond. This should be a negligible diameter, otherwise light leaks out of the bottom. Tolkowsky's ideal dimensions did not include a culet. However, a thin culet is required in reality in order to prevent the diamond from easily chipping in the setting. A normal culet should be about 1%–2% of the overall diameter.

The further the diamond's characteristics are from Tolkowsky's ideal, the less light will be reflected. However, there is a small range in which the diamond can be considered "ideal." Today, because of the relative importance of carat weight in society, many diamonds are often intentionally cut poorly to increase carat weight. There is a financial premium for a diamond that weighs the magical 1.0 carat, so often the girdle is made thicker or the depth is increased. Neither of these tactics make the diamond appear any bigger, and they greatly reduce the sparkle of the diamond. So a poorly cut 1.0 carat diamond may have the same diameter and appear as large as a 0.85 carat diamond. The depth percentage is the overall quickest indication of the quality of the cut of a round brilliant. "Ideal" round brilliant diamonds should not have a depth percentage greater than 62.5%. Another quick indication is the overall diameter. Typically a round brilliant 1.0 carat diamond should have a diameter of about 6.5 mm. Mathematically, the diameter in millimeters of a round brilliant should approximately equal 6.5 times the cube root of carat weight, or 11.1 times the cube root of gram weight, or 1.4 times the cube root of point weight.

Ideal cuts can be controversial as the definitions of brilliance and beauty are very subjective.

Developed circa 1900, the round brilliant is the most popular cut given to diamond. It is usually the best choice in terms of saleability, insurability (due to its relatively "safe" shape), and desired optics.

Facet count and names
The modern round brilliant (Figure 1 and 2) consists of 58 facets (or 57 if the culet is excluded); 33 on the crown (the top half above the middle or girdle of the stone) and 25 on the pavilion (the lower half below the girdle). The girdle may be frosted, polished smooth, or faceted. In recent decades, most girdles are faceted; many have 32, 64, 80, or 96 facets; these facets are excluded from the total facet count. Likewise, some diamonds may have small extra facets on the crown or pavilion that were created to remove surface imperfections during the diamond cutting process. Depending on their size and location, they may hurt the symmetry of the cut and are therefore considered during cut grading.

Figure 1 assumes that the "thick part of the girdle" is the same thickness at all 16 "thick parts". It does not consider the effects of indexed upper girdle facets. Figure 2 is adapted from Figure 37 of Marcel Tolkowsky's Diamond Design, which was originally published in 1919. Since 1919, the lower girdle facets have become narrower


For more diamond information, a specific diamond requirement or loose diamonds, please contact our London diamond department : info@hirschfelds.co.uk.
020 7405 1536. +44 20 7405 1536 from overseas.

Pearshape diamonds, Oval diamonds, Radiant diamonds, Princess Cut diamonds, Marquise diamonds, Ascher, Emerald Cut diamonds, Baguette diamonds. Click here to discover interesting "D" Colour Diamond information. View our gorgeous collection of Old Cut diamonds, diamond rings and jewellery

 Coloured diamonds London , Certificated Diamonds London Certified Diamonds. Hatton Garden Diamonds London.

We wholesale diamonds, natural fancy coloured diamonds London. Yellow diamonds, Green diamonds, Pink diamonds, Orange diamonds, Purple diamonds. They can be supplied in various shapes and sizes.We have stocks of loose diamonds such as - Loose briliant cut diamonds, Loose Oval diamonds, Loose Emerald Cut Diamonds.

This magnificent blue diamond has broken all records when it was sold by Sotheby's Geneva May 2009 for $9.5 million. The 7.03 carat diamond fetched the highest price per carat for any gemstone ever sold at auction as well as a record auction sum for any vivid blue diamond sold in the past.

We are The first London diamond shop front for wholesale loose diamonds and second hand diamonds. We have clients and customers who rely on our diamond services throughout The UK, England, Wales Scotland. N Ireland & Eire. We therefore offer a Nationwide - United Kingdom insured "Special Delivery" (Registered Post) postal service is available throughout Great Britain for all your diamond special orders

We are buyers of diamonds. We are especially interested in buying antique diamonds, purchasing old cut diamonds and vintage cushion diamonds. We buy old mine cut diamonds secondhand Edwardian diamonds and Victorian diamonds. We can recut diamonds repolish chipped diamonds and polish rough diamonds too. Click her for all ourLondon jewelleryrepair services.

We are located in the the heart of London's historic jewellery quarter of Hatton Garden close to Clerkenwell, Cheapside, Covent Garden, Baker Street, Marylebone, Bloomsbury, Barbican, Holborn, Fleet Street, Central London, Islington, Smithfield, Soho, St Pauls, Oxford Street, Bond Street, The West End, Westfield & The City of London. Hatton Garden London, being a unique district on the fringe of the City in central London, is located within the area bounded by Clerkenwell Road, Gray's Inn Road, Holborn and Farringdon EC1 London England UK.
Close to EC2, EC3, EC4, W1, W2, WC1, WC2, N1, NW1, NW3, NW8, SW1, SE1, E1
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