Jubilee Diamond

The Jubilee Diamond, originally known as the Reitz Diamond is a colourless, cushion-shaped diamond weighing 245.35 carats (49.07 grams), making it the sixth largest diamond in the world. It was originally named after Francis William Reitz, the then president of the Orange Free State where the stone was discovered, before being renamed to honour the 60th anniversary of the coronation of Queen Victoria in 1897.

The original stone, a rough octahedron weighing 650.80 carats (130.16 g), was discovered in 1895 at the Jagersfontein Mine in South Africa. A consortium of diamond merchants from London purchased it along with its even larger sister, the Excelsior, in 1896, and sent it to Amsterdam where it was polished by M.B. Barends. A 40 carat (8 g) chunk was removed, which itself yielded a 13.34 carat (2.668 g) pear-shaped gem eventually purchased by Dom Carlos I of Portugal.

The Millennium Blue Diamonds, with the Heart of Eternity at the center.

Nicky Oppenheimer was careful not to put a value on the Millennium Star, saying that any figure he would give would be purely academic. The London Evening Star was not as conservative as Mr. Oppenheimer and insured the Star for 100 million English pounds. This is believed to be a fraction of its true worth. Beny Steinmetz, Co-Chairman of the Steinmetz Diamond Group, echoed the cautious approach of Oppenheimer, but pointed out that the previous record price paid for any polished diamond was $16.5 million for a 100.10 carat D-Flawless stone, the Star of the Season, that was auctioned by Sotheby's in May, 1995, thus selling for about $165,000 per carat. According to market sources, that stone was also manufactured and sold by the Steinmetz group. To the two senior principals of the Steinmetz Group, brothers Beny and Danny Steinmetz, it is rather symbolic that they were chosen to cut the De Beers Limited Edition Millennium Diamond. It is exactly 50 years ago, almost to the day, that the Steinmetz Diamond Company was established by the late Ruben Steinmetz, father of the present principals. "Ruben Steinmetz was known for manufacturing high quality goods," recalls his son, and, without saying so, one could sense that the sons are truly moved by their ability to continue family tradition. Nobody will ever "accuse" the hard and successful businessmen, what the Steinmetzes are, of being sentimental. But in the presence of the Millennium stones times stands still and one must reflect on one's past, one's roots and on the future.

The Heart of Eternity

It was expected that some 12-million people would visit the De Beers Millennium Jewels Exhibition at the Millennium Dome in London. There they were on view in a specially designed exhibit for the entire year of 2000. It is worth it to pause a moment and reflect on the rarity of blue diamonds. Pre-20th century accounts of great blue diamonds reinforce the trade's historical links with India, the only known early source of diamonds. These accounts tell of diamonds such as Tavernier Blue (now known as the Hope Diamond; 45.52 carats) and the 30.82-carat Blue Heart, which today are valued for their history and mystique as much as for their rare color. These diamonds are famous because of their incredible rarity - only red diamonds are rarer - and the De Beers collection of blues is something that will never be seen again.

Florentine Diamond

The Florentine Diamond is a lost diamond of Indian origin. It is light yellow in colour with very slight green overtones. It is cut in the form of an irregular (although very intricate) nine-sided 126-facet double rose cut, with a weight of 137.27 carats (27.454 g). The stone is also known as the Tuscan, the Tuscany Diamond, the Grand Duke of Tuscany, the Austrian Diamond and the Austrian Yellow Diamond.

Excelsior Diamond

The Excelsior Diamond was found on June 30, 1893 at the Jagersfontein Mine by a worker while loading a truck. The man was able to hide the diamond from the supervisors but delivered it to the manager of the mine himself. Until 1905, when the larger Cullinan diamond was found, the Excelsior was the largest known diamond in the world. It had a blue-white tint and weighed 971¾ carats (194.2 g). It was ultimately cut into ten stones weighing from 13 to 68 carats. (2.6 to 13.6 g). Immediately after its discovery the news spread around the world.

The Excelsior I, the largest gem cut from the crystal, was eventually bought by jeweler Robert Mouawad.

Crown (headgear)

A crown is the traditional symbolic form of headgear worn by a monarch or by a deity, for whom the crown traditionally represents power, legitimacy, immortality, righteousness, victory, triumph, resurrection, honour and glory of life after death. In art the crown may be shown being offered to those on Earth by angels. Apart from the traditional form, crowns also may be made of, for example, flowers, stars, oak leaves or thorns and be worn by others, representing what the coronation part aims to symbolize with the specific crown. They often contain jewels.

Iranian Crown Jewels

The Imperial crown jewels of Iran (also known as the Imperial crown jewels of Persia) include several elaborate crowns and decorative thrones, thirty tiaras, and numerous aigrettes, a dozen bejewelled swords and shields, a vast number of unset precious gems, numerous plates and other dining services cast in precious metals and encrusted with gems, and several other more unusual items (such as a gemstone globe) collected by the Iranian monarchy during its 2,500-year existence.

Hardware

HTC opted for resistive technology for the touchscreen but not capacitive. The reason cited by Horace Luke, HTC's Chief Innovation Officer, was that the resistive touch screen is better for Asian character recognition.^[12] However, the buttons beneath the screen, as well as being pressable buttons, have capacitive touch sensitivity. This feature is used by the camera application to auto-focus the camera as a finger approaches to press the button that will take a picture.^[13]

Luke also noted that this is the thinnest device that HTC has designed to date.^[14]

Some people find that the Touch Diamond's battery life is too short to suit their needs, although it is possible to greatly extend this with an upgrade to the 'radio rom'. Consequently, batteries offering double the capacity of the included battery are being sold by third parties and HTC itself sells an extended battery with 50% extra capacity. ^[15][16]

The screen turns itself off when a person is on a call. This is to prevent the screen accepting unwanted inputs from the user's face when they are making a call, but it also requires the user to turn the screen back on if they want to use the screen. Removing the stylus when in a phone call both turns on the screen and starts up the notes application. ^[17]

HTC Touch Diamond

The HTC Touch Diamond, also known as the HTC P3700 or its codename the HTC Diamond^[1], is a Windows Mobile 6.1-powered Pocket PC designed and manufactured by HTC. It is the first device to feature TouchFLO 3D - a new version of the TouchFLO interface, unique to the Touch family.^[2] The HTC Touch Diamond was first available in Hong Kong in late May 2008.^[3][4] It was available across all major European carriers in June 2008, and will be available later in the year in other parts of the world^[5]. The American Touch Diamond was launched on September 14 2008 on the Sprint^[6] network, and April 10, 2009 on the Verizon Wireless network^[7]. The European release date was slightly delayed by a last-minute ROM update.^[8] The carrier bound names for this phone include T-Mobile MDA Compact IV^[3], O2 XDA Diamond^[9] and O2 XDA Ignito.^[10] It is the official successor of the HTC Touch.^[11] The successor to the Touch Diamond - the HTC Touch Diamond2 - was announced in February 2009 for Q2 2009 release outside the US and Q4 release estimated for North America.

Imperial State Crown

The Imperial State Crown is one of the British Crown Jewels.

The Crown is of a design similar to St Edward's Crown: it includes a base of four crosses pattée alternating with four fleurs-de-lis, above which are four half-arches surmounted by a cross. Inside is a velvet cap with an ermine border. The Imperial State Crown includes several precious gems, including: 2,868 diamonds, 273 pearls, 17 sapphires, 11 emeralds, and 5 rubies.

The Crown includes several famous jewels. The Cross atop the Crown is set with a stone known as St. Edward's Sapphire, a sapphire taken from the ring (or possibly coronet) of Edward the Confessor. The Black Prince's Ruby (actually a spinel) is set on the front cross pattée. Furthermore, the famous Cullinan II, or Lesser Star of Africa, is set on the front of the Crown. The back of the crown is set with the 104 carat (20.8 g) Stuart Sapphire in its band, directly above Cullinan II, is the Koh-i-Noor, which was once set into the tiara of the Queen Mother, and until recently, kept separate from the rest of the Crown Jewels, the Koh-i-Noor was placed into the Imperial State Crown shortly after the death of the Queen Mother in 2002.

Imperial State Crown

It is generally worn at the end of a coronation when the new monarch departs from Westminster Abbey and is not normally the actual crown used at the moment of coronation. However it was actually worn during the ceremony by Queen Victoria and King Edward VII, both of whom complained about the weight of the normally used crown, St Edward's Crown.

The Imperial State Crown is worn annually by the Queen at the State Opening of Parliament. Traditionally, the Crown and other jewels leave in their own carriage and arrive at the Palace of Westminster prior to the Queen's departure from Buckingham Palace. They are then transported to the Robing Room, where the Queen dons her robes and wears the Crown.

The current Imperial State Crown was manufactured for the coronation of King George VI in 1937 by the Crown Jewellers Garrard & Co. It is an exact replica of the earlier Imperial State Crown manufactured for Queen Victoria, but is of a more lightweight design and less uncomfortable to wear. The same Crown was remodelled for Queen Elizabeth II’s coronation to give it slightly more feminine appearance and its total height lowered by about one inch (2.54cm). Because of its weight (910 g), monarchs often choose to wear the Imperial State Crown in their private apartments on and off for a couple of hours on the morning of the State Opening of Parliament so they can get used to the weight and feel comfortable with it on. (One courtier reported on the morning of a State Opening witnessing Queen Elizabeth eating her breakfast and reading newspapers while wearing it.)

Imperial State Crown

The Imperial State Crown is one of the British Crown Jewels.

The Crown is of a design similar to St Edward's Crown: it includes a base of four crosses pattée alternating with four fleurs-de-lis, above which are four half-arches surmounted by a cross. Inside is a velvet cap with an ermine border. The Imperial State Crown includes several precious gems, including: 2,868 diamonds, 273 pearls, 17 sapphires, 11 emeralds, and 5 rubies.

The Crown includes several famous jewels. The Cross atop the Crown is set with a stone known as St. Edward's Sapphire, a sapphire taken from the ring (or possibly coronet) of Edward the Confessor. The Black Prince's Ruby (actually a spinel) is set on the front cross pattée. Furthermore, the famous Cullinan II, or Lesser Star of Africa, is set on the front of the Crown. The back of the crown is set with the 104 carat (20.8 g) Stuart Sapphire in its band, directly above Cullinan II, is the Koh-i-Noor, which was once set into the tiara of the Queen Mother, and until recently, kept separate from the rest of the Crown Jewels, the Koh-i-Noor was placed into the Imperial State Crown shortly after the death of the Queen Mother in 2002.

Small diamond crown of Queen Victoria

The Small Diamond Crown of Queen Victoria was a miniature crown created at the request of Queen Victoria of the United Kingdom in 1870. It was perhaps the crown most associated with Queen Victoria. Such was the association that it, and not either the traditional St. Edward's Crown or her own Imperial State Crown, was placed on her coffin before her funeral

Princess cut From Wikipedia, the free encyclopedia

The Princess cut is the second most popular cut shape for diamonds, next to a round brilliant. The face-up shape of the princess cut is square or rectangular and the profile or side-on shape is similar to that of an inverted pyramid with four beveled sides. The princess cut is a relatively new diamond cut, having been created in the 1960s. It has gained in popularity in recent years as a more distinctive alternative to the more popular round brilliant cut, in which the top of diamond, called the crown, is cut with a round face-up shape and the bottom, called the pavilion, is shaped similar to a cone. A princess cut with the same width as the diameter of a round brilliant will weigh more as it has four corners which would otherwise have been cut off and rounded to form a round brilliant. The princess cut is sometimes referred to as a square modified brilliant. However, while displaying the same high degree of brilliance, its faceting style is quite unique and completely different from that of a round brilliant. The Princess cut had its origins in the early "French" cut, having a step-modified "Double-French" or "Cross" cut crown and a series of unique, chevron-shaped facets in the pavilion which combine to give a distinct cross-shaped reflection when the stone is viewed directly through the table. Effectively, the Princess cut combines the high degree of light return of a round brilliant cut with a distinctive square or rectangular shape.

The square princess cut diamond is usually slightly cheaper than round brilliant cut diamonds of the same carat weight because it retains about 80% of the rough diamond, as opposed to the round brilliant which retains only about 50% of the rough. The ability to retain more crystal weight makes this shape popular amongst diamond cutters.

Accredited Gem Appraisers (AGA) and American Gem Society Laboratory (AGSL) and European Gem Laboratories-USA (EGL-USA) are currently the only labs that grade the Princess cut for cut. There is no universal definition of what measurements make an ideal princess cut diamond and many diamond manufacturers market ideal diamonds with differing facet patterns and angles as "ideal cut". In contrast to the AGSL, AGA, and EGL-USA the Gemological Institute of America (GIA) has stated that there is not enough industry consensus or empirical data to specify cut grading standards for Princess cut diamonds and to do so is at the risk of consumers who may be deceived by diamonds accompanied by unqualified Ideal or Excellent cut grades.

The name "Princess Cut" was originally used in connection with another diamond cut, otherwise known as the "Profile" cut, designed by Arpad Nagy a London cutter in 1961. The same name was later used and made popular by Ygal Perlman, Betzalel Ambar, and Israel Itzkowitz in Israel in 1979. A similar cut with only 49 facets, as opposed to the original 58 facets of the princess cut, was later branded the "Quadrillion" and initially distributed by Ambar Diamonds in Los Angeles. Three years of optical research yielded a square stone with faceting similar to that of a round brilliant cut diamond.

The Cullinan II Diamond.

Imperial State Crown: originally made for Queen Victoria's coronation in 1838, it was remade for George VI in 1937. It contains the 317.40 carat Cullinan II. The large stone above the Cullinan II is the Black Prince's Ruby, which is actually a red spinel. The stone was at one time a giant bead. Note the red dot on the upper part of the stone - that is a ruby that was used to plug a small hole that went right through the stone. The Stuart Sapphire is a very fine 104-carat oval shaped sapphire that appears on the backside of the crown. It was amoung the Crown Jewels of Charles II. The sapphire in the center of the cross on the top of the crown is St. Edward's Sapphire, (believed to have belonged to Edward the Confessor), and the four large drop-shaped pearls are said to have been Elizabeth I's earrings.

The Cullinan

he Black Prince's Ruby on the front of the Imperial State Crown, a name which is misleading because the stone is actually a red spinel weighing about 170 carats. The gem is a large bead - the lighter-colored dot on the front of the stone is actually a ruby plugging up the hole that goes through the stone. Photo © HMSO,

The Cullinan

Late one afternoon in 1905, Mr. Frederick Wells, the superintendent of the prolific Premier Mine in South Africa, was making a routine inspection trip through the mine when his attention was attracted by something reflecting the last slanting rays of the setting sun. Curious, he stopped for a closer look. He was eighteen feet below the surface of the earth, and the shiny object was on the steep wall of the mine a few feet above him. Mr. Wells quickly scaled the wall and extracted from the blueground what appeared to be a large diamond crystal. At first, he thought he was being fooled by a large piece of glass, but tests proved it to be the largest gem-quality diamond ever discovered. It weighed 3106 carats, or about 1⅓ pounds. It was named after Sir Thomas Cullinan, who opened the mine and was visiting on that eventful day. Many diamond experts believe that the huge stone was only a fragment, and that another piece, (possibly as large or even larger) either still exists and awaits discovery, or was crushed in the mining process. The latter is very unlikely. The prospect of finding the portion of the Cullinan has added zest to the activities of numerous miners and prospectors. The Cullinan was sold to the Transvaal government, which presented it to King Edward VII on his 66th birthday on November 9th, 1907. It was insured for $1,250,000 when it was sent to England. The King entrusted the cutting of the stone to the famous Asscher's Diamond Co. in Amsterdam, which had cut the Excelsior and other large gems. T

Cullinan Diamond

The Cullinan diamond is the largest rough gem-quality diamond ever found, at 3,106.75 carats (621.35 g).^[1]

The largest polished gem from the stone is named Cullinan I or the First Star of Africa, and at 530.2 carats (106.0 g) ^[2] was the largest polished diamond in the world until the 1985 discovery of the Golden Jubilee Diamond, 545.67 carats (109.13 g), also from the Premier Mine. Cullinan I is now mounted in the head of the Sceptre with the Cross. The second largest gem from the Cullinan stone, Cullinan II or the Lesser Star of Africa, at 317.4 carats (63.5 g), is the fourth largest polished diamond in the world. Both gems are in the Crown Jewels of the United Kingdom.

Koh-i-Noor

The Kōh-i Nūr (Hindi: कोहिनूर, Persian/Urdu: کوہ نور, Telugu: కోహినూరు) which means "Mountain of Light" from Persian, also spelled Kohinoor, Koh-e Noor or Koh-i-Nur is a 105 carat (21.6 g) diamond that was once the largest known diamond in the world. The Kohinoor originated at Golconda in the state of Andhra Pradesh in India. It has belonged to various Sikh, Mughal and Persian rulers who fought bitterly over it at various points in history and seized it as a spoil of war time and again. After completely ignoring Maharaja Ranjit Singh's will^[1] it was finally seized by the East India Company and became part of the British Crown Jewels when British Prime Minister Benjamin Disraeli proclaimed Queen Victoria Empress of India in 1877.

Dresden Green Diamond

The Dresden Green diamond is a 41 carats (8.2 g) natural green diamond that has a historical record dating to 1722, when a London news-sheet carried an article about it in its 25 October-27th edition.^[1]

It is named after the capital of Saxony, Germany where it has been on display for most of the last two centuries. In 2000, American jeweler, Harry Winston arranged to display the Dresden Green in their New York Grand Salon and then at the Smithsonian in Washington DC, USA , where it was displayed in the Harry Winston pavilion next to the largest blue diamond in the world, the Hope diamond.

The stone's unique green color is due to natural exposure to radioactive materials (see Diamond enhancement#Irradiation). The stone is being used to compare natural versus lab-produced green diamonds — it is hoped that it can be used to devise a test to differentiate between naturally green diamonds, which are quite rare, and lab-produced ones.^[2]

This diamond is located in the Staatliche Kunstsammlungen Dresden "The New Green Vault" ^[3]

Noor-ol-Ain Diamond

The Noor-ol-Ain is the principle diamond mounted in a tiara of the same name made for Iranian Empress Farah Pahlavi's wedding to Shah Mohammad Reza Pahlavi in 1958. The Diamond is believed to have been recovered from the Golconda mines in India and was brought into the Iranian Imperial collection after the conquest of that country by Nader Shah Afshar in the 18th century.

It is one of the largest pink diamonds in the world and is believed to have once formed part of an even larger gem. That larger diamond is thought to have been cut in two, with one section becoming the Noor-ol-Ain and the other the Darya-ye Noor diamond. Both of these pieces are currently part of the Iranian Crown Jewels.^[1]

Noor-ol-Ain translated from Persian (via Arabic loan) means the light of the eye.

Irradiation

Sir William Crookes, a gem connoisseur as well as a chemist and physicist, was the first to discover radiation's effects on diamond color when in 1904 he conducted a series of experiments using radium salts. Diamonds enveloped in radium salt slowly turned a dark green; this color was found to be localized in blotchy patches, and it did not penetrate past the surface of the stone. The emission of alpha particles by the radium was responsible. Unfortunately radium treatment also left the diamond strongly radioactive, to the point of being unwearable ^[2]. A diamond octahedron so treated was donated by Crookes to the British Museum in 1914, where it remains today: it has not lost its color nor its radioactivity.

Nowadays diamond is safely irradiated in four ways: proton and deuteron bombardment via cyclotrons; gamma ray bombardment via exposure to cobalt-60; neutron bombardment via the piles of nuclear reactors; and electron bombardment via Van de Graaff generators. These high-energy particles physically alter the diamond's crystal lattice, knocking carbon atoms out of place and producing color centers. Irradiated diamonds are all some shade of green, black, or blue after treatment, but most are annealed to further modify their color into bright shades of yellow, orange, brown, or pink. The annealing process increases the mobility of individual carbon atoms, allowing some of the lattice defects created during irradiation to be corrected. The final color is dependent on the diamond's composition and the temperature and length of annealing.

Cyclotroned diamonds have a green to blue-green color confined to the surface layer: they are later annealed to 800°C to produce a yellow or orange color. They remain radioactive for only a few hours after treatment, and due to the directional nature of the treatment and the cut of the stones, the color is imparted in discrete zones. If the stone was cyclotroned through the pavilion (back), a characteristic "umbrella" of darker color will be seen through the crown (top) of the stone. If the stone was cyclotroned through the crown, a dark ring is seen around the girdle (rim). Stones treated from the side will have one half colored deeper than the other. Cyclotron treatment is now uncommon.

Gamma ray treatment is also uncommon, because although it is the safest and cheapest irradiation method, successful treatment can take several months. The color produced is a blue to blue-green which penetrates the whole stone. Such diamonds are not annealed. The blue color can sometimes approach that of natural Type IIb diamonds, but the two are distinguished by the latter's semiconductive properties. As with most irradiated diamonds, most gamma ray-treated diamonds were originally tinted yellow; the blue is usually modified by this tint, resulting in a perceptible greenish cast.

Thermal and electrical

Diamond is an extremely effective thermal conductor and usually an electrical insulator. The former property is widely exploited in the use of an electronic thermal probe to separate diamonds from their imitations. These probes consist of a pair of battery-powered thermistors mounted in a fine copper tip. One thermistor functions as a heating device while the other measures the temperature of the copper tip: if the stone being tested is a diamond, it will conduct the tip's thermal energy rapidly enough to produce a measurable temperature drop. As most simulants are thermal insulators, the thermistor's heat will not be conducted. This test takes about 2–3 seconds. The only possible exception is moissanite, which has a thermal conductivity similar to diamond: older probes can be fooled by moissanite, but newer Thermal and Electrical Conductivity testers are sophisticated enough to differentiate the two materials. Latest development is nano diamond coating, a nano layer of diamond material. If not tested properly it may show the same characteristics as a diamond Diamond Testing.

A diamond's electrical conductance is only relevant to blue or gray-blue stones, because the interstitial boron responsible for their color also makes them semiconductors. Thus a suspected blue diamond can be affirmed if it completes an electric circuit successfully.

The ring Main article: Engagement ring

The origin of the custom to use diamonds in rings, and more recently, in engagement rings, can be traced back to the Middle Ages and even the Romans. The Romans valued the diamond entirely on account of the supernatural powers they ascribed to it. Pliny wrote that a diamond baffles poison, keeps off insanity, and dispels vain fears.^[18] The medieval Italians copied these beliefs and added some to it: they called it the "Pietra della Reconciliazone" because it maintained concord between husband and wife. On this account it was recommended as the stone to be set in wedding (or espousal) rings—not on account of its beauty therefore, which was described by Isidore of Seville as a small stone devoid of beauty.^[18]

In more recent times a Parisian Oracle of mystic subjects, the Baron d'Orchamps, announced the diamond, if worn on the left (hand) warded off evil influences and attracted good fortune and since he had fashionable clients the word spread and the wearing of the diamond on the left hand became in itself a fashion.^[21]

One of the first occurrences of the diamond engagement (or wedding) ring can be traced back to the marriage of Maximilian I (then Archduke of Austria) to Mary of Burgundy in 1477.^[22] Other early examples of betrothal jewels incorporating diamonds include the Bridal Crown of Blanche (ca. 1370–80)^[22] and the Heftlein brooch of Vienna (ca. 1430–40),^[22] a pictorial piece depicting a wedding couple.

The popularity of the diamond ring as an engagement ring for a much wider audience can be traced directly to the marketing campaigns of De Beers, starting in 1938.^[23] Such a campaign had become necessary to sell the large quantity of diamonds suddenly available because of the large diamond finds particularly in South Africa.

Process Main article: Diamond cutting

The process of shaping a rough diamond into a polished gemstone is both an art and a science. The choice of cut is often decided by the original shape of the rough stone, location of the inclusions and flaws to be eliminated, the preservation of the weight, popularity of certain shapes amongst consumers and many other considerations. The round brilliant cut is preferred when the crystal is an octahedron, as often two stones may be cut from one such crystal. Oddly shaped crystals such as macles are more likely to be cut in a fancy cut—that is, a cut other than the round brilliant—which the particular crystal shape lends itself to.

Even with modern techniques, the cutting and polishing of a diamond crystal always results in a dramatic loss of weight; rarely is it less than 50%. Sometimes the cutters compromise and accept lesser proportions and symmetry in order to avoid inclusions or to preserve the carat rating. Since the per carat price of diamond shifts around key milestones (such as 1.00 carat (200 mg)), many one-carat diamonds are the result of compromising "Cut" for "Carat." Some jewelry experts advise consumers to buy a 0.99 carats (200 mg) diamond for its better price or buy a 1.10 carats (220 mg) diamond for its better cut, avoiding a 1.00 carat (200 mg) diamond which is more likely to be a poorly cut stone

Cut Main article: Diamond cut

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 defined the ideal dimensions as:

• 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 (200 mg), so often the girdle is made thicker or the depth is increased. Neither of these tactics make the diamond appear any larger, and both greatly reduce the sparkle of the diamond. So a poorly cut 1.0 carat (200 mg) diamond may have the same diameter and appear as large as a 0.85 carats (170 mg) 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 (200 mg) 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.

Tolkowsky's mathematical model is now superseded by the GIA Facetware software that is the culmination of 20 years of studies on diamond cuts.

New diamond cuts are now all the rage in the diamond industry as for example a design invented in 2003 and called the Genesis cut. This cut differs in shape from the more traditional cuts in its concave surfaces and angles and resembles a 4-pointed star.

Color

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 "colorless" and Z having a bright yellow coloration)[1], 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 color grade, along with standardized and carefully controlled lighting conditions. Diamonds with higher color grades are rarer, in higher demand, and therefore more expensive, than lower color grades. Oddly enough, diamonds graded Z are also rare, and the bright yellow color is also highly valued. Diamonds graded D-F are considered "colorless", G-J are considered "near-colorless", K-M are "slightly colored". N-Y usually appear light yellow or brown.

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

Main article: Diamond color

The most fine quality as per color grading is totally colorless which is Graded as "D" color diamond across the globe which means it is absolutely free from any color. The next is very slight traces of color which can be observed by any expert Diamond valuer/grading laboratory. However when studded in the jewelery these very light colored diamonds do not show any color or it is not possible to make out color shades. These are graded as E color or F color Diamonds. Diamonds which show very little traces of color are graded as G or H color diamonds. Slightly colored diamonds are graded as I or J or K color. A diamond can be found in any other color also other than colorless. Some of the color diamonds such as pink are very rare diamonds and are priceless.

A chemically pure and structurally perfect diamond is perfectly transparent with no hue, or color. However, in reality almost no gem-sized natural diamonds are absolutely perfect. The color 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 color 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. The Aurora Diamond Collection displays a spectacular array of naturally colored diamonds.

Grading white diamonds

The majority of diamonds that are mined are in a range of pale yellow or brown color that is termed the normal color range. Diamonds that are of intense yellow or brown, or any other color are called fancy color diamonds. Diamonds that are of the very highest purity are totally colorless, and appear a bright white. The degree to which diamonds exhibit body color is one of the four value factors by which diamonds are assessed.

[edit] History of color grading

Color grading of diamonds was performed as a step of sorting rough diamonds for sale by the London Diamond Syndicate.

As the diamond trade developed, early diamond grades were introduced by various parties in the diamond trade. Without any co-operative development these early grading systems lacked standard nomenclature, and consistency. Some early grading scales were; I, II, III; A, AA, AAA; A, B, C. Numerous terms developed to describe diamonds of particular colors: golconda, river, jagers, cape, blue white, fine white, and gem blue, "brown"

Diamond color From Wikipedia, the free encyclopedi

Type II diamonds have no measurable nitrogen impurities. 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. Type IIa diamond can be colored 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 color; these are not necessarily Type IIb.

Also not restricted to type are green diamonds, whose color is derived from exposure to varying quantities of radiation.

Possible colors Main article: Diamond type

Diamonds occur in a variety of colors — steel gray, white, blue, yellow, orange, red, green, pink to purple, brown, and black. Colored 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 percent^{[citation needed]} 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).

Aurora Butterfly of Peace From Wikipedia, the free encyclopedia

Two research studies involving the Butterfly of Peace have resulted in new scientific breakthroughs about fluorescence and phosphorescence in fancy colored diamonds. The amazing phenomena of fluorescence can be seen as a skeletal pattern of glowing colors when the diamonds are exposed to ultraviolet light. There are rare and unusual color diamonds that make up the design including purples from Russia, blues and oranges from South Africa, lime greens from Brazil, violets and dozens of pinks from the Argyle Mine in Australia.

Aurora Butterfly of Peace From Wikipedia, the free encyclopedia

The Aurora Butterfly of Peace diamond collection is an artwork consisting of 240 natural, fancy colored diamonds weighing a combined total of 167 carats (33 g). This butterfly-shaped diamond mosaic was created over a period of twelve years by Alan Bronstein and Harry Rodman. The diamonds were collected and assembled one stone at a time. The Aurora Butterfly of Peace was conceived by the artists as an eternal icon of love, beauty, energy, nature, peace. It symbolizes a spiritual connection to earth for all mankind.

From November 2004 through July 2005, the Butterfly of Peace was exhibited in the National Gem Collection Gallery at the Smithsonian Institution in Washington, D.C.

A smaller version of the Butterfly of Peace was displayed at the Houston Museum of Natural Science from June 1994 through March 1996. The Aurora Butterfly of Peace was on display from May 25 to July 30, 2008 at the Museum of the Gemological Institute of America (GIA), to help launch “The Facets of the GIA” exhibit, which showcases the prominent role of the Institute in the world of gemology.

Simulants Main article: Diamond simulant

A diamond simulant is defined as a non-diamond material that is used to simulate the appearance of a diamond. Diamond-simulant gems are often referred to as diamante. The most familiar diamond simulant to most consumers is cubic zirconia. The popular gemstone moissanite (silicon carbide) is often treated as a diamond simulant, although it is a gemstone in its own right. While moissanite does look similar to diamond, its main disadvantage as a diamond simulant is that cubic zirconia is far cheaper and arguably equally convincing. Both cubic zirconia and moissanite are produced synthetically.^[87]