We’ve talked a great deal here about the history and value of diamonds here. What we’ve not really spent any time on, however, is how a diamond’s value gets established in the first place. Do they pull a number out of a hat? Do they sacrifice a chicken?
You’ll be happy to know they don’t. Though they might as well read entrails for all the good that does you if you don’t understand what is going on. For that reason, today we’re going to address that oversight by giving you more insight. In that way, you’ll know what diamond appraisers are going to look at. That will allow you to judge whether what they are telling you is the truth or is so much hogwash.
That’s not the only thing we’re going to talk about, either. We’re also going to discuss which gemology groups are the more reputable ones. So that, even if you can’t judge with a high degree of accuracy the quality of the appraisal, at least you know if can trust the appraiser.
And that is almost as good!
The appraisal process
A diamond is appraised on four different dimensions. These are:
- Carat or the weight of the diamond.
- Color where less color is more valuable.
- Cut is how the diamond is proportioned.
- Clarity the fewer faults (also called ‘inclusions’) the more valuable.
That’s not so hard, right? Let’s look at all these in more detail, so that you get a better sense what to look out for on those four dimensions.
Carats are the most straightforward of the four dimensions to measure. You can do so with any sensitive scale. One carat is 0.2 grams or a little more than 0.007 ounces. So if your stone weighs 1/10th of an ounce, you’ve got a 14 carat diamond.
Note that if your diamond is set in a setting, weighing it will obviously be a lot harder. In this case, the number of carats the diamond has can be measured by way of its dimensions. This is only an approximation, though.
The basic color rule is pretty straightforward. More expensive diamonds have less color. How is color measured? There are a few ways that this can be done, but the most popular way is to compare a stone to a master set.
Your stone is then awarded the color grading of the stone it most closely matches. Now, there are different color-grading scales, advanced by different gem institutes. In the US the one you’re the most likely to run into is the one created by the Gemological Institute of America or GIA.
Stone color runs from D to Z, where D, E and F are almost completely colorless and G to J stones are pretty damned close. You’ll generally only see a yellowish tint in stones rated from K to Z.
The better the cut the more valuable the diamond. This is because better cut diamonds look better. Not only that, they will trap and return the most light to the viewer’s eye, thereby giving the stone more sparkle.
There are many dimensions are considered when the cut of a diamond is evaluated. Here are a few of the more important ones:
- The girdle: This is the thin slice at the broadest part of the diamond that separates the top of the stone (also known as the crown) from the bottom. It is what the setting will make contact with. This should be rated from ‘thin’ to ‘medium’. Too thin and it may chip.
- Table percentage: This is calculated by dividing the diameter or width of the stone’s top most facet by the width or diameter of the girdle. The perfect relationship is 54 to 57%.
- Depth percentage: This is calculated by taking the total depth (or height) of the stone and how this relates to the girdle’s width. Here the desired dimension is 61 to 62.5%
- Crown Angle: This is the angle measured from the girdle towards the table top. The angle here should be at 34 to 35%.
- Pavilion Angle: This is the angle in the other direction towards the point of the diamond. The desired angle here is 40.6 to 41%
Note that these dimensions are for round cut diamonds, which are the most likely ones you’ll find.
Then, finally, there is clarity. Clearer and more valuable diamonds have fewer faults, like carbon spots or lines.
The bigger the fault the more it affect value more. If you can see a fault with the naked eye, then will reduce the value of the stone a lot. On the other hand, if it can’t even be seen with a 10x magnification, then it’s not considered significant enough to affect clarity at all.
Note that a lot of these dimensions are a lot harder to assess when the diamond is in its setting. I already mentioned that it’s much harder to weigh a stone that way. That’s not the only thing that is affected, though.
For example, the color can be a lot harder to assess. This is particularly true if the setting isn’t white. Similarly, inclusions or faults can be difficult to spot when the stone is not taken out.
For that reason, don’t be surprised if the appraiser asks to take the stone out of the setting to evaluate it. That’s perfectly normal. At the same time, if you don’t trust the appraiser, then don’t leave them alone with the stone, so they can’t switch it while you’re away.
Which labs can you trust?
Finally, let’s discuss the different labs that are out there. The four best known are:
- The Gemological Institute of America (GIA)
- The American Gem Society (AGS)
- The European Gemological Laboratory (EGL)
- The International Gemological Institutes (IGI)
Generally, you’d be better of getting your diamonds rated by the first two, as these are considered more reputable.
Having a certification is not only good for you, but good for our listed diamond buyers as well. They can make an estimate for your diamond from the appraisal information provided by these organizations quickly and easily (final offers are typically made after examination to confirm).
Many industry insiders strongly advise you to avoid IGI certified diamonds. This is because they frequently overrate their diamonds. That means you’re going to pay an inflated price.
It won’t help you if you get the stone you’re holding assessed by them either. For in many markets you’ll often be offered a lower price for the same grade when they’ve rated it. This is because diamond experts are aware of IGI’s tendency to overrate and figure this into the prices they are willing to pay.
So yes, the IGI might be cheaper to use than the others, but this comes with a price!
So there you have it! A crash course in what to look out for in your diamond as well as what companies you should use. Armed with this knowledge you’ll be better prepared. For you’ll have a better idea of what your stone is worth, what to look for in the diamonds you’re buying and how to get it certified as accurately as possible.
And that will mean that when you buy and sell diamonds you’re in a much better position to get the best deal you can get. Now isn’t that a nice bit of peace of mind?