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Diamond Grading, Grades

When purchasing certified diamonds it is important to understand the diamond grading criteria used by the laboratories performing the certification.

Diamond grading covers numerous aspects of each individual diamond’s qualities, but there are four grades which are critical to understand: cut, clarity, color, and carat weight. There are additional ratings and measurements noted on a diamond certificate, but they generally fall under the diamond’s grade in one of the Four Cs. For example, measurements listed such as “depth” and “table” are part of the description of the diamond’s cut.

You can learn more about how diamonds are graded by reading the articles listed below.

Diamond Cut

Cut is probably the most important quality factor, and most challenging, of the four Cs to understand. The brilliance of a diamond depends heavily on its cut. More info…

Diamond Clarity

Most diamonds contain some inner flaws, or inclusions, that occur during the formation process. The visibility, number and size of these inclusions determine what is called the clarity of a diamond. Diamonds that are clear create more brilliance, and thus are more highly prized, and priced. .

Diamond Color

Colourless diamonds are the most desirable since they allow the most refraction of light (sparkle). Off white diamonds absorb light, inhibiting brilliance.

Carat Weight

A carat is the unit of weight by which a diamond is measured. Because large diamonds are found less commonly than small diamonds, the price of a diamond rises quickly as its size increases.

 

The larger a diamond the more expensive it is and as we rise up the scale of size the prices rise dramatically. There are key price points 0.25,0.5,0.75,1.0,1.25,1.5,1.75.2.0,2.5.3.0,3.5,4.0,4.5,5.0.The reality is that a 0.97 carat can be a lot cheaper than a 1 carat. People often like to be able to have an exact number a 1 carat weight is a key point. In the business we often refer to an 80 pointer which means 0.8 of a carat or we may refer to a stone as being a one fifty which means that it is one and a half carats.

The Fifth C: Certificates

The diamond certificate, which is sometimes called a grading report, is a complete evaluation of your diamond that has been performed by a qualified professional with the help of special gemological instruments. Each stone bears its own recognizable, individual characteristics, which is listed on the certificate. The most recognised certificate in the business is the GIA certificate. The IGI and HRD are also widely recognised and highly thought of.

There are various other certificates around but the bottom line is if you buy one of the above it will be exactly what it says on the certificate!!The EGL certificate has not got the greatest reputation and should be treated with great caution. We will not accept anything we read on an EGL cert unless we verify it independently with our gemologist. Having said all that EGL certed stones are cheaper and the odd bargain does come through.

There are also some uncarted stones which doesn’t mean they are bad –some manufacturers simply want to turn the stone around quickly and are doing so in high volumes and hence the stone is uncerted. This is often the case in smaller stones of less than one carat.

The reality in larger more valuable stones is that they should be certed and there is no reason that they should be offered uncerted.

 

 

Diamond Fluorescence refers to the diamonds tendency to emit a soft coloured glow when subjected to ultraviolet light.

Before we get into the details our overall opinion. Fluorescence should not influence your decision to purchase a diamond. Diamond Fluorescence is a hotly debated topic in the diamond industry, but a 1997 study by the GIA suggests fluorescence makes very little difference to the appearance of the diamond.

In the diamond industry, the existence of fluorescence in a diamond (caused by the natural mineral properties of the diamond), has caused many debates and has, in many instances, influenced the pricing of diamonds.


Natural Light


UV Light

Simulated fluorescence

Simulated fluorescence
It is common to find that diamonds with colourless grades (D-E-F) or near colourless grades (G-H-I-J) are lower in price when they exhibit fluorescence.
A GIA study selected a group of similarly graded diamonds with varying degrees of fluorescence to be observed and commented on by study participants. Participants in the study included: trained diamond graders, trade professionals (e.g., jewellers), and average observers (general jewellery buying public).

Here’s a quote from the study:
“For the average observer, meant to represent the jewellery buying public, no systematic effects of fluorescence were detected. Even the experienced observers did not consistently agree on the effects of fluorescence from one stone to the next.

“In general, the results revealed that strongly blue fluorescent diamonds were perceived to have a better colour appearance when viewed table-up [ed: right-side up, as when placed in a setting] with no discernible trend table-down [ed: upside-down]. Most observers saw no relationship between fluorescence and transparency.”
In other words, for the average observer fluorescence made no difference and experienced observers (diamond graders and trade professional) did not agree on the influence of fluorescence. And contrary to previous theories, the experienced/trained observers most consistently determined that diamonds with strong fluorescence were the ones with the best color.

Bottom Line on Fluorescence
Don’t let flourescence unduly influence your choice when selecting a diamond.

If industry experts can’t agree on the influence of flourescence and constantly split hairs over its effect, we feel it falls into the range of minutiae that simply serves to confound and confuse, rather than inform the diamond buying public.

However, because of industry debate and prejudice (which appears unfounded), you may find colourless or near-colourless diamonds that exhibit fluorescence have slightly lower prices than those that do not. Our opinion? Enjoy the better value!!

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