Fracture filling is a process whereby tiny internal fractures to the diamond’s structure are treated or filled to lessen their visible impact both to the naked eye and when under normal (10X) magnification.
Fractures are a natural and quite common that occurs during the tens of thousands of years that it takes to create a natural diamond. Over the course of years, the raw diamond is slowly forced from the earth’s core up through the crust towards the surface. During this period, the rock bearing the diamond crystal and diamonds themselves, are subject to extreme pressure and heat which cause the appearance of tiny imperfections or bubbles of trapped air and other physical characteristics within the stone. Some of these physical characteristics will later be used by gemological laboratories such as the GIA to provide each diamonds individual and unique “ID”, others, like the tiny fractures, can be treated to make them less visible.
Note: Don’t be put off by the term “fracture”. These are internal imperfections and in no way affect the diamonds structural integrity. However, they can significantly affect the diamonds reflective index (the way light is reflected and bounced inside the stone) and removing them can greatly increase a diamonds sparkle and brilliance.
Evidence exists that the Chinese used wax and oil to disguise internal fractures in jade over 2500 years ago. However the brilliance of a diamond is so much greater than that of jade and many other precious stones that an entirely new technique and materials had to be developed.
This new technique was first developed in Israel during the 1980’s. A diamond expert, Zvi Yehuda, developed a technique for injecting, under pressures of about 50 atmospheres and at a temperature of around 400 °C, a material that filled these tiny fractures. This original technique did leave its mark in the form of tiny air bubbles trapped inside the injected material, a tendency to distort of flow when the filled diamond was placed under extreme heat and flashes of orange to blue light coming from the filled stone.
Note: The original fracture filled diamonds were often represented as untreated stones. However, since the diamond industry is based on trust, this practice soon stopped and all reputable dealers will always state, up front, if the diamond has been fracture filled.
The exact formula used to fill diamond fractures is a closely guarded secret. Each company that uses this process has their own, special formula and fracture filled diamonds are often sold under that company’s brand name.
As we mentioned earlier, fracture filling, even today, is detectable by a trained gemologist. But there are other ways the filling can effect a diamond. For example, with regard to the “flash” effect, this can be less obvious in colored diamonds when the stones natural color will filter out some of the color wavelengths.
Another aspect to be aware of is that the solution used to fill fractures is not necessarily 100% transparent and colorless. In fact, it will often have a yellowish, brown tint. This tint can adversely affect a diamond’s color grading, reducing by as much as an entire grade level. That’s why fracture filling is more common in larger stones where this color degrading is less obvious.
Fracture filling of diamonds has been a controversial issue from the very start of the modern process when the original developer, Zvi Yehuda, sold fracture filled diamonds without informing his customers that they had been treated.
Today, the majority of reputable diamond merchants and dealers will tell you if their diamonds are fracture treated or not. Knowing this can be critical if, at some later stage, your diamond jewelry is sent for repair of to have a new setting made. These processes often involve intense heat (often in the region of 1400 °C which can cause the diamond’s filling material to discolor and, in some case, even flow.
There is no one, internationally accepted standard with regard to certification of fracture treated diamonds. Some diamond labs such as the internationally acclaimed and accepted GIA does not issue certificates for fracture filled diamonds whilst others, such as IGL will issue a certificate for these diamonds that clearly states that the diamond has been fracture filled.
Other labs may issue certificates that relate to the diamonds original state and clarity and fail to mention if the stone has been fracture filled. This, for the reasons we gave earlier, can be misleading and potentially dangerous in terms of maintaining your diamond in tip top condition.
Note: The majority of diamond dealers and merchants realize that honesty and transparency (forgive the pun) is the only policy. This is true of all business transactions, but especially the diamond industry where deals involving hundreds of thousands of dollars are sealed with a hand shake. If in doubt – ask your jeweler directly if your diamonds are fracture filled.
Finally, a general rule that is valid for all your diamond transactions – beware of Greeks bearing gifts. In other words, if someone is trying to sell you a diamond at well under its market value and claims that it isn’t enhanced in any way – check it out very carefully because something isn’t right. Diamonds are expensive and one of the benefits of enhanced diamonds are their lower prices (typically 40% lower than an unenhanced equivalent diamond).
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