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The Centenary Diamond

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The Centenary Diamond Owned by De Beers

The Centenary is one of the world’s largest modern cut diamond weighing 273.85 carat, measured 39.90 × 50.50 × 24.55 mm, and had 247 facets – 164 on the stone and 83 around its girdle.

The Gemological Institute of America (GIA) (Read here for GIA gemologist class) graded its color as D (Read here for color of Diamond) and its clarity as Flawless.   The rough diamond weighed 599 carats and was found in July 1986 in the Premier Mine in South Africa.

Using the most sophisticated electronic cutting instrument at that time it took the famous master cutter Mr. Gabi Tolkowsky three years to prepare, cut and polish this stone.

Specialized Equipment Being Used To Cut The Centenary Diamond

The equipment used for cutting this stone is specifically designed to hold it securely with pipes to circulate cooling liquid.  The small blue wire is connected to a 9 thermal probe to monitor the temperature generated during the cutting process.

The Centenary Diamond is owned by De Beers Consolidated Mines Limited and was unveiled for public view for the first time in London on May 1st 1991 by De Beers’ Deputy Chairman Mr. Nicky Oppenheimer.

What a stunning beauty in so small a stone….

Citation & Sources : http://en.wikipedia.org/wiki/Centenary_Diamond, http://famousdiamonds.tripod.com/centenarydiamond.html

Diamonds Under the Scope

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Diamond Inclusions: Diamonds are formed deep under the earth’s surface for millions of years under extreme heat and pressure. Naturally, this give rise to a number of imperfections inside a diamond, which are called inclusions, as well as on its surface, which are called blemishes. When viewed under a 60X or a 120X microscope, the inclusions of a diamond reviewed a fascinating world.

The article below is written by Sharon Bohannon of GIA and is reposted here from www.gia.edu

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Diamonds Under the Scope

Another world exists in gemstones when they are viewed through a microscope. Landscapes and whimsical creatures appear to come to life as you explore a gem’s internal features and formations.
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Inclusions spin a tale of provenance and tell of the diamond’s journey from deep within the earth to the surface. They are a geological time capsule that tells a story of a gem’s formation. Feather inclusions in a diamond, for example, can be indicative of a rough ride from the earth’s mantle to the surface. These birthmarks are signs of a diamond’s natural origin and make your diamond unique in the world.

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In 1645 an Englishman saw a red crystal inclusion (probably a garnet) in a diamond belonging to a Venetian nobleman by the name of Rugini. This discovery sparked an interest in colored crystal “guest” minerals or inclusions in diamond. A number of crystal mineral inclusions have been reported since then.

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Inclusions impart character, beauty and essence to their host gems.

Dr. Edward J. Gübelin  

The renowned Swiss gemologist Dr. Edward J. Gübelin (1913-2005) built a legacy on the study and systematic classification of the internal world of gemstones. His research demonstrated the importance of these internal features in determining a gem’s identity.

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John I. Koivula, GIA’s analytical microscopist and long time chief research gemologist, wrote to Dr. Gübelin as a teenager, sending along his first photomicrographs (photos taken through a microscope). This began a collaboration that would culminate in the three-volume “PhotoAtlas of Inclusions in Gemstones,” landmark works that established the importance of inclusions as an aid to identifying gemstones. Their photomicrographs of inclusions illustrate common features in gemstones from particular localities. Their richly illustrated tomes also help separate natural from synthetic or treated gemstones, including diamonds.

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Diamonds present some of the most striking inclusions to view under the microscope and host a variety of gemstone guest crystals. Some of the most frequently found are pyrope garnet, olivine or peridot, diopside, chrome-spinel, and much less frequently, ruby and sapphire. Diamond crystals are also frequently seen as inclusions within diamond itself.

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The study and documentation of inclusions in diamond has inspired poetic and descriptive names: feather, cloud, halo, knot, needle, bearding and pinpoint.  With magnification, these scenes are clues to the natural origin of a diamond and give you a renewed appreciation for its characteristics and qualities. The possibilities of what you can see in these photomicrographs is almost endless.

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A Magnificent Colored Diamond & Ring

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A magnificent color diamond and diamond ring sold on May 27, 2014 in Hong Kong at the Christie’s Auction for HK$46,040,000  (US$5,965,527).


Set with a pear-shaped fancy intense pink diamond weighing approximately 9.38 carats, flanked by pear-shaped diamonds, mounted in platinum and 18k rose gold, ring size 7.
Accompanied by report no. 8758558 dated 30 April 2010 from the Gemological Institute of America stating that the 9.38 carat diamond is fancy intense pink, natural color.

pink diamond combi
約9.38 克拉梨形濃彩粉紅色鑽石戒指,附GIA證書,配以鑽石,
鑲鉑金及18k 粉紅金,戒指尺寸7

Source : www.christies.com/

 

 

 

 

 

 

 

 

 

Diamond Misshapen Facets

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Graphic Representation of a Round Brilliant Cut Diamond

If you are buying some loose diamonds for your own personal setting, the quality will be assured if the diamonds are accompanied by a GIA Diamond Report or a GIA Diamond Dossier.

However, for smaller stones which are not being graded by GIA, then you will have to depend on the integrity of the seller for what he represents to you on the quality.  Your seller may without the least intention to misrepresent his products, however, most of the time the Sales Associate or Sales Rep may not be aware of the quality of diamonds his/her employer is selling.  These are the traders and retailers who depend on the representation of the quality by their own up-line suppliers.

The Color and Clarity grade of a diamond may be difficult to determine for one without experience in grading diamonds and without the proper equipment.  Even the cut of a diamond may be difficult to ascertain.  Say, if you are buying a loose diamond without a GIA grading report, the best is for you to look for the Cut which is not cut to the proportions of an ‘ideal cut’ diamond, instead of looking for the excellent qualities in the loose diamond.

You might be surprised that the human eye is very sharp when it comes to seeing dis-proportionate cut diamonds and it can pick up asymmetrical inconsistencies with a 10X loupe.

The graphic representations below and some brief notes will put you in good footing when it comes to buying some loose diamonds without GIA Grading reports.


http://www.stellarjewelry.com, http://www.americandiamond.com,

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Pink Diamond Auction For $45.62 Million

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A model displays a 24.78-carat Fancy Intense Pink Diamond

A 24.78 ct pink diamond was sold at CHF 45.44 million (USD45.62 million) in an auction held by the Sotheby’s in Geneva on Tuesday, 16 November 2010, breaking the record for any diamonds and jewelry ever sold at an auction.

The 24.78 Fancy Intense Pink Diamond

The diamond was bought by the British billionaire jeweler A Laurence Graff, who is a Jewish English jeweler and is best known as a supplier and buyer of unique jewellery and rare jewels.

Laurence Graff - The Extraordinary Billionaire Jeweler

The pink diamond, graded as Fancy Intense Pink by the Gemological Institute of America (GIA), is described by the Sotheby’s as “exceptionally rare and truly magnificent pink diamond of the purest, vibrant hue,” with type IIa classification which comprises less than 2 percent of all gem diamonds in the world.

The diamond was purchased some 60 years ago from Harry Winston and it has been preserved as a personal collection since then, until it was auctioned off by Sotheby.

http://news.xinhuanet.com, http://www.gemselect.com, http://www.sotheby.com

Diamond Ring With Faked Ascending Diamonds

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A 3ct Diamond With Ascending Diamonds

Hi Arthur

I have a 3ct diamond solitaire ring with some small diamonds set on the side.  Last month one of the small diamond dropped off.  I went to a local goldsmith and they set it back for me.  They said the diamond weight was about 7point.  I paid a reasonable amount of money for the replacement diamond and the workmanship.

The center diamond is no problem.  On viewing my ring when I am back home, I am uncomfortable with the smaller diamonds.  Would they give me a faked diamond or would they change some of the smaller diamonds?

I am not familiar with this goldsmith as I have just being posted to this new place.

Thank you

Angela

Beijing, China

Hi Angela

It is very difficult for a non gemologist to distinguish a ‘faked’ diamond from a real one by using a loupe.

This happened to me many years ago when I was not in the jewelry trade yet.  My wife has a solitaire diamond of 0.5ct and she went to set a gold ring with 14 ascending stones.  The small stones were from the goldsmith.  The goldsmith was known to us.

When I came home from New York City I examined her ring with a loupe.  I discovered that a few of them were not diamonds.  On testing them with a Diamond Tester, 4 of them could not pass the test.  There were Cubic Zirconia.

Since it was many years ago that she set the diamond ring, we could not take it back to the goldsmith.

Now, I would not accuse the owner of the goldsmith for giving me CZs and charging me the full price of the diamond.  The owner may give to his bench work goldsmith setter the real diamonds and there were being swapped by the goldsmith at the bench work.

I have heard of a number of cases too where the smaller diamonds were swapped or the jeweler set it with CZ and charged the customers the full price of diamonds.

Say, for your case, a 7 pointer diamond may be worth about US$55, while a CZ would be less than a dollar.  By swapping the stones, the setter would be able to fleece his superior if there are no proper quality control procedures within the jewelry shop.

What you can do is to bring it back to the goldsmith and asked them to test each of the smaller diamond with a Diamond Tester.  If it does not pass the test then there are not diamonds.

(Note : the only stones that are not diamonds and could pass the test of a diamond tester is Moissanite, which may be difficult to acquire and may be more expensive.)

So the next time you send your jewelry for repair, ensure that the small diamond pieces are tested before you by the sales assistant using a Diamond Tester.  Most of the jewelers have this instrument.   This way you will be protected against fraudulent practices.

A.Arthur Lau

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