18. GIA grading

Almost all diamonds sold online, and better quality larger stones sold in the stores, come with a (supposedly) independent 3rd party grading report, or 'cert'. Reports help you ‘compare apples’ - but sadly there is no international standards body - different labs can give the same stone different grades.

The well known 3rd parties are GIA, AGS, IGI and EGL.


GIA grading reports are the most common listed on the web (about 3/4's of all listings). So let's take a look what it look like.



Topics that included :

17. Pro and Con to shop diamond online!

Although it may seem like a risky venture, buying over the Internet can be a very safe way to buy the most beautifully cut diamonds at the best prices.

Pros:

Selection - By shopping online, you can find the best-cut (most beautiful) diamonds. This is because many Internet vendors list entire wholesaler inventories, whereas most stores that buy diamonds to have in stock can only buy so many and may not have the knowledge or desire to stock the best-cut diamonds.

Prices - The Internet prices are highly competitive because of lower operation cost for some and many dealers are competing to sell the very same diamonds. (There are some Internet or brick and click vendors who maintain their own inventory). In addition, you can save on taxes by getting the diamond shipped to you from another state.

Flexibility - One benefit of Internet shopping is the ability to have diamonds shipped to you where you can view them in the lighting conditions where they will be worn. Consumers can also take a diamond shipped to them to a local jeweler to make comparisons. Just be aware of the return policy of the vendor from whom you buy.

Cons:

Uncertainty – How can I be sure that I'll get what I'm paying for?

Lack of trust – How do I know whether the vendor whom I've never met will provide what he promised?

Doubts – How can I be sure that I’ll be able to get my money back if I am not satisfied?

To take advantage of the pros and avoid the cons we suggest you to consider these simple rules of common sense:

Educate yourself
Compare prices
Check vendors
Get independent appraising

For more information - visit this website : http://www.pricescope.com/isitsafe.asp

16. Diamond Weight Estimation

This is for estimating the weight of loose diamonds. I found this information from website of Mr.Ryan Thompson (http://famousdiamonds.tripod.com/diamondweightestimation.html)

This section was originally "Gemstone Weight Estimation", but he realized the formulas were meant for diamond.
3.52 is the specific gravity of diamond.

Here are the estimation calculation

Rounds = Diameter x Diameter x Depth x .0061
Ovals = Length x width x Depth x .0062
Princess Cuts = Length x width x depth x .0083
Heart Cuts = Length x width x depth x .0059
Triangle Cut = Length x width x depth x .0057


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Emerald Cut = Length x width x depth x factor:



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Marquise Cut = Length x width x depth x factor:



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Pear Cut = Length x width x depth x factor:

15. 'Champagne', 'Cognac' and 'Coffee'

What do the terms 'champagne', 'cognac' and 'coffee' mean pertaining to diamond color?

These refer to different types of brown. In the diamond processing/dealing industry, the word 'brown' is considered a killer as far as diamond value goes. Outside the diamond processing/dealing industry, nobody seems to care. Even though champagne the drink is a light yellow color, champagne diamonds are light brown. Congac is usually used to describe a diamond that is orangy-brown or brownish-orange because cognac is a deep golden orange color. Coffee is usually used to describe a diamond that is a deep brown color. Those are dressed-up term the jewelry industry uses to describe brown diamonds. I tend to call them what they are, however. The GIA will call them something like Fancy Intense Brown or Fancy Yellowish-Brown or Fancy Light Brown, etc. I have not seen a diamond grading certificate for a brown diamond that didn't have secondary colors. Whenever I have seen a certificate mentioning brown, it has always been something like Fancy Brownish-Pink, Fancy Brownish-Yellow, Fancy Yellowish-Brown, Fancy Orangy-Brown, and so on. I've never seen a Fancy Brown or a Fancy Intense Brown. I think the reason is that most people with diamonds like this don't get them certified (unless they have a larger stone like 3 or 4 carats or more) because in the world of colored diamonds, brown diamonds tend to fall towards the bottom of the price scale. In other words, most people would not consider it worth the money to get the stone certified. Like I have said elsewhere on this site, the most common gem-quality diamonds in nature are light yellow or light brown. Black is even more common usually as industrial rough and only some black diamonds are faceted, even though they are opaque stones they must first show certain potential.

Reference : http://famousdiamonds.tripod.com/faq.html

14. Diamond vs Cubic zirconium.

The different between a diamond and a cubic zirconium.

Well-cut cubic zirconium can compete with diamond, but when held side-by-side with a diamond, there is a visual difference. A colorless cubic zirconium tends to cast some rainbow reflections within it, called 'fire'. A colorless or near-colorless diamond doesn't tend to -- most of the sparkle is shades of gray and white. Cubic zirconium is manufactured in numerous different colors including different shades of pink, yellow, purple, blue, orange, red, brown, colorless and even opaque black. CZ is an 8½ on the Mohs hardness scale, about the same as topaz. CZ is also much more dense than diamond with a specific gravity of 5.8 while diamond is just 3.5. (In other words, a piece of CZ is going to weigh about 75% more than a piece of diamond of identical mass. Some CZ is grown with different formulas, which means the 75% figure isn't always true.) Diamond has a refractive index of 2.42. CZ has a refractive index of about 2.15, making it brighter than quartz, topaz, corundum and other materials, but not as bright as diamond.

Reference : http://famousdiamonds.tripod.com/faq.html

13. Lucky number - let's talk about the rumors

1.The stone 'the Heart of the Ocean' in Titanic was based on the Hope Diamond.

This is true. James Cameron has admitted to basing the stone on the Hope. The Hope is a cushion shape surrounded by white diamonds on a necklace, and the Heart of the Ocean is a heart shape (and much much larger than the Hope) also surrounded by white diamonds, on a necklace. Sometime after the film was made, a large fine sapphire was discovered and cut into a heart shape and placed into a necklace identical to the prop used in the film - except with genuine stones. The necklace was worn by Celine Dion at several events, and was later sold for over $1 million. This is one of the rare cases in the history of fine jewelry where a genuine stone was cut based on a fake, rather than vice-versa.


2.There really was a Heart of the Ocean necklace that sank with the Titanic.

This is false. Nor was the Hope Diamond (the gem the Heart of the Ocean was based on) ever on the Titanic. Evalyn Walsh McLean, however, owned the Hope Diamond from 1910 up til her death in 1947, and she had considered booking a trip on the Titanic's maiden--and only--voyage in 1912. Fortunately, she decided not to.


3. Diamonds are the most valuable gemstone in the world.?
This seems like it should be true, but its not. Diamonds are very valuable in the world of gems, but a fine ruby is actually worth more. There are far more large diamonds in this world than there are large rubies. The Mogok Ruby presently holds the world record for the most valuable ruby, in terms of the highest price fetched at a sale. It is a 15.97-carat rectangular cushion cut sold by Sotheby's of New York in October 18th, 1988 for $3,630,000 ($227,301 per-carat). The stone is untreated, that is, it was not heated to improve its color. It was purchased by Laurence Graff of London, who reportedly sold it to the Sultan of Brunei as an engagement ring for one of his wives. The Mandalay Ruby is the largest faceted ruby I have ever heard of, but I do not know whether it is the largest.

Reference : http://famousdiamonds.tripod.com/faq.html

12. The largest faceted diamond

The largest faceted diamond in the world is the Golden Jubilee, weighing 545.67 carats. It is a Fancy Brownish-Yellow color and "fire rose cushion cut." It is unusual also because it has a certain type of rare color banding. The second largest faceted diamond in the world is the Star of Africa, also known as the Cullinan I. It weighs 530.20 carats and is a pear shape with 74 facets. The third largest diamond in the world is the Incomparable. It is a golden yellow-orange color, pear shaped, and weighs 407 carats. The fourth largest faceted diamond in the world is the Cullinan II. It was cut from the same stone as the Star of Africa - aka Cullinan I. It weighs 317.40 carats and is a cushion cut.

Up until 2001, the most valuable diamond (price-per-carat) was the 0.95-carat fancy red Hancock Red that had been sold at auction at Christies, NYC, for $880,000 ($926,315 per-carat). The stone was apparently purchased by a buyer representing the Sultan of Brunei, who reputedly has one of the largest collections of fancy colored diamonds in the world. I am not exactly sure which diamond holds the world record for the highest price per-carat, but I am almost certain its no longer held by the Hancock Red. Time will tell!

Reference : http://famousdiamonds.tripod.com/famousdiamonds.html