How to Read a Certificate
Note: This page only covers certificates. For a more
comprehensive list of FAQs, go to our Index of Consumer
According to the
lawyers, GIA issues only a "Diamond Grading Report"
and not a "certificate," warranty, or guarantee of
any kind. But since everyone calls it a diamond certificate, we will
continue to use that term here to avoid confusion.
Always use a certificate from a reputable lab to
compare diamonds and their prices -- and to avoid costly mistakes.
IMPORTANT: Whenever you have questions about
diamonds, rely on a good, honest jeweler for answers. We rated the best internet jewelers and
created an exclusive network of the best local jewelers
in most major areas -- so you would have somewhere to start your search for the truth about diamonds.
REMEMBER: A dishonest jeweler can cheat you, no matter how much you know. And an honest jeweler will give you a great deal, no matter how little you know. Invest the greatest energy and time in finding a good dealer first, then you will always get a great deal on any diamond you want. Let the jeweler use their connections in the industry to find your diamond.
Make It Simple ==========
We have tried to be brief in this report while providing
the details necessary to make the best decision about your diamond.
If the information seems overwhelming, you might want to consider calling a good jeweler, and ask them to help you wade through all of it. It is always faster that way, and you will learn a lot more when you look at stones in person.
And if you are ready to focus on calculating a fair and competitive price for your diamond, go to our Diamond Pricing Tutorial page. That guides you step-by-step through the fastest and most accurate way to price any diamond.
Print Sample Certificates ==========
To make the most from this report, we suggest printing examples
of your favorite lab certificate to follow along as you read
the explanations below. Use these direct links to the samples
of each cert on the official laboratory web sites: (these links are accurate as of Mar 1, 2012)
GIA reports =
Diamond Grading Report and Diamond Dossier
AGS reports =
Platinum Diamond Quality Document
Diamond Quality Document
Diamond Quality Certificate
Diamond Quality Report
Diamond Quality Analysis
EGL USA reports =
European Gemmological Laboratories USA (as opposed to EGL anywhere else)
Please don't tell me you are using any other lab report. It would not make either one of us very happy in the end. Stick to these labs, please.
FAQ -- Frequently
Do the same guidelines apply for smaller diamonds, like the ones
that might be used for side stones?
The answer depends on the size of the diamonds you use on the
side. All diamonds above 0.46 carats in weight should be judged
on the basis of the guidelines we have given in this report.
Therefore, if you will be purchasing a 2-carat diamond for the
center stone, you might want to design a ring with side stones
that weigh about 0.50 carats each, or whatever looks in good
proportion to your eye. In that case, the usual guidelines would
apply. But keep in mind that some people put less emphasis on
quality in the side stones. We recommend matching the color of
the center stone, but perhaps considering side stones with somewhat
Why a certificate?
The value of a good lab certificate when buying a diamond is undeniable.
If you do not receive a diamond grading certificate from an unbiased,
independent, respected laboratory, you are not getting the diamond
you are being promised.
First, about half of all diamonds are overgraded by one color
grade and one clarity grade -- to make them easier to sell. This
may not sound like much, but for a 1-carat diamond it can easily
mean $1,000 or more in lost value. A certificate from a respected,
independent laboratory will give an accurate, unbiased assessment
to help you avoid this problem.
Second, every diamond is unique. This makes a diamond purchase
very different from buying a brand-name automobile with a list
of options you can look up in a price list. There is no comprehensive
diamond price list because the list would have to include millions
of possible combinations of weight, color, clarity, girdle thickness,
etc. -- about 22 factors in all. Not even the well-known Rapaport
price list is enough, since it only gives the basic starting
point with prices for about 10,000 combinations of four best-known
factors of shape, size, color, and clarity. If you try to calculate
a diamond price from the Rapaport alone, without considering
the remaining 18 factors that dealers use, you could easily be
off by 30% or more and end up overpaying for a poor-quality diamond.
An unbiased certificate supplies all the essential details and
allows a complete assessment of a stone's basic value.
Third, it would be very difficult and time-consuming for a layperson
to learn enough to properly assess all the complex factors of
diamond quality and pricing. It is not practical to take six
months of in-residence training to become a gemologist for an
item you only buy once in a lifetime. Without sufficient knowledge,
you will certainly miss some tiny factor that means a great deal
to the value. A detailed certificate saves you enormous amounts
of time by supplying an expert evaluation.
A diamond grading certificate from one of the better labs is
the first, crucial step in getting what you want for fair price.
Aren't all gemological labs the same?
Definitely not. Most smaller gem labs are extensions of local
jewelry stores, created solely for the purpose of raising the
image of the store's inventory. But such labs are hardly unbiased
and the certificates are rarely accurate. To make it simple,
if you want an honest assessment of a diamond's true quality,
avoid any lab that is not one of those listed below:
GIA -- Gemological Institute of America
The most widely respected laboratory in the world today. Certs
from this lab are in such demand that diamonds with a GIA cert
are often priced 30-50% higher. This premium is also due to the fact
that the diamond is truly the stated quality, since GIA is known
for its conservative grading. All labs can make a mistake,
but GIA labs have been the most consistent for decades.
AGS -- American Gemological Society
This was the only large, nationally respected lab that assigns
a grade to the overall cut of a diamond. Now they all give cut grades, using varying criteria for each grade.
More on that in my future blog, or the upcoming new website. Certs from AGS are often
used for all Ideal Cuts, and describe all the details of the
cut to verify perfect proportions. If you want a perfect cut
above anything else, you should insist on an AGS cert.
EGL-USA -- European Gemological Laboratories
Several related labs around the world operate under this network. Please focus on certs from the EGL-USA network of labs. EGL certs from other labs around the world are NOT as reliable yet. The grades at the non-USA labs are not as reliable, and that reflects on the value of the diamond. EGL-USA labs are consistent in our opinion.
AGL -- American Gemological Laboratory
This lab is best known for its work in the colored stone industry,
working to provide expert assessments of gemstone identification,
treatments, and enhancements. The diamond certs have recently
gained a reputation as consistent and conservative.
IGI -- International Gemological Institute
This lab is working to improve its reputation and grading
standards, but it will take some time to convince us that the
bugs are worked out. They tend to grade diamond higher than GIA, AGS, and EGL-USA.
Note About Other Labs
Other labs may be highly qualified and offer excellent information.
However, other labs do not enjoy the same reputation and popularity
as those listed above, and therefore will not command as much
value if you ever need to sell the diamond. In the worst scenario
-- and a very common one -- other labs will not grade the diamond
properly and you are not receiving the actual quality of diamond
you want. In most cases, you will end up paying too much for
a diamond of lesser quality with certificates from other labs.
Are all diamonds priced the same?
You should also understand that all stores price diamonds differently.
Some have lower markups, some higher. Some have poor credit or
low volume, so they pay more for the same diamonds and must charge
more just to break even. Most stores have some combination of
these situations, creating a wide range of prices for the same
The best proof of this is found on the Internet. If you search
several different sites, you might find the exact same diamond
listed by different companies. Many sites access the same national
inventory from a common database. You will find that each store
offers that diamond at a different price. If you want to know
the best places to buy, read our independent Dealer Ratings.
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to Read a Certificate