In my Diamond Treatments tutorial, the focus was really more on colorless diamonds. Today I’m going to be revisiting this topic and to talk a little bit about how fancy colored diamonds are enhanced, without going in too deep about the topic, which is very complex.
Understanding the value of natural fancy colored diamonds requires appreciating how rare they occur in nature. Remember that the Cape series of diamonds are part of the most common class of diamonds, type1a, and have a degree of yellow tint depending on the nitrogen impurities that are present. On the other hand, only around 0.1% of diamonds belong to the type1b class of diamonds that produces a canary yellow colored diamond.
Apart from this, when we talk about fancy colored diamonds, we are dealing with type2 diamonds that have no nitrogen impurities at all. Generally in a perfect crystal, a type2a diamond is colorless. It is actually the distortions in the crystal growth of a type2a diamond that causes many beautiful fancy colors such as pink. Finally there is the type2b diamond, which has impurities of the element boron. Only around 0.1% of natural diamonds are type2b and these are generally blue in color.
Green fancy colored diamonds are caused by natural irradiation, which is extremely rare and this makes green fancy colored diamonds one of the most expensive colors. This also causes problems for identification because artificial irradiation is one of the ways that color can be induced into a treated diamond. It is my understanding that if GIA cannot identify whether the irradiation is natural that they will classify the diamond as ‘undetermined’.
The difficulty of identification is the reason why you may find that sometimes a part of the rough diamond is left on a natural green diamond so that the rough part can be tested to authenticate its natural origin. Known artificially irradiated diamonds will not be certified by the GIA because the color is not considered permanent because the color will actually change on subsequent heating.
Another way to induce color is through the high-pressure, high-temperature (HPHT) process. I have discussed a version of this process that is used to turn a type2a diamond colorless. The HPHT process is used to enhance type1a diamonds that are naturally brown to make them into more desirable colors.
It is pretty tough to find an unbiased opinion on unnatural diamonds on Pricescope as most diamond prosumers there are advocates for natural diamonds. There is good reason for this.
First, you want to make sure that receiver of the diamond will actually like a fancy colored diamond. More importantly, you need to make sure that the ultimate wearer of the treated diamond understands and accepts the treatment. There really isn’t any point in passing off a treated diamond as a natural diamond and doing so is akin to passing off a diamond simulant as a real diamond.
Those of you who follow my articles will know that I am an advocate that every gem has its market. So my advice is that if you’re in the market for one of these stones, then make sure you understand the product and its value and if you’re okay with how much you’re paying for it then sure, go for it.
What I don’t like are vendors who stress that a color treated diamond is a ‘natural diamond’, just that the color is not natural. Yes there is a distinction, but the important point that must be conveyed to the purchaser is that the color treatment severely impacts the price of the diamond over its natural counterpart.
But it is because of this same point that I will not simply advise someone to never purchase a treated gem. If you want the look of a fancy colored diamond and simply cannot afford the price of a natural fancy colored diamond, then there really isn’t a worthwhile debate. If you’re hard set on a colored diamond, I don’t see a good enough reason for anyone to try to convince you that you should settle on a colorless diamond either.
The tricky thing about treated fancy colored diamonds is when it comes to determining value for money. Natural colored diamonds are cut not for their light performance, rather to enhance their color. You will also know from my Fancy Colored Diamonds tutorial that the cutting philosophies are entirely different.
Logically, a treated type1a diamond should cost what it did before the treatment plus the premium of the treatment. But in the case of a treated colored diamond this may not be the case. For example, a diamond that is cut deep and may not be a well-cut diamond as a colorless gem may be more valuable as a colored gem. Be aware of this as a potential sales tactic and bear in mind what the original stone may cost and then decide what you’re willing to pay for the treatment and that should be a reasonable price.