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Fracture Filling of DiamondsDiamond 4 C'sChard 24 Carat Home Page

Fracture Filled Diamond
Fracture Filled Diamond

View from Underside
View from Underside

Fracture Filling of Diamonds
Clarity is one of the importance 4Cs of diamond quality. Fracture filling is one method of clarity enhancement. On this page we go into more detail about fracture filling.

Fracture Filling
Although there must have been many earlier attempts at filling open cracks and fissures in diamonds and other gemstones, the first commercial fracture filling of diamonds was done by Zvi Yehuda of Israel in 1982, and the Yehuda Diamond Company. Although the exact process remains secret, much is known about the materials and processes used. Since then, other companies have started to fracture fill diamonds using process which are believed to be slightly different, but there are a number of similarities between all filling processes.
Most of the process use a special glass formulation, and inject it molten into the cavities using high pressure, probably under a vacuum, and at varying high temperatures.

Yehuda
The Yehuda process is thought to utilise temperatures of around 400°C. It can be detected in numerous ways, but the easiest and best known is the "flash effect". Yehuda clarity enhanced diamonds are known to show a greater flash effect than other more recent processes.

Koss
Koss Diamonds, also of Israel, are one of the other well-known clarity enhancers Their process is estimated at 600°C.
Koss enhanced diamonds are said to display less noticeable flash effect than most Yehuda stones.

Goldman Oved
Sometime around 1990, the Goldman Oved company also started fracture filling using a process requiring between 500 to 550° Celsius.

Oved
Oved Diamonds of New York developed a new filling with higher temperature resistance in about 2000. This apparently upset Yehuda by claiming that it was resistant to the high temperatures used in jewellery repair, and the GIA ran some comparison trials.

Detection
There are a number of ways to detect facture filled diamonds, and these include the flash effect already mentioned, flow structure, gas bubbles, crackled texture, incomplete filling, cloudy surface, cloudy filled area, melting, and other loss of filling.
We will shortly be adding more detail here about these various detection methods.

Photographs
Don't ask why the two photographs we show of the same fracture filled diamond appear different colours, much of this effect was probably due to a quirk in the photographic process and lighting, although some of it may be attributable to the filling. The main features to observe are the unnatural flashes of colour which can be seen in the top view, and some strange lines which can also be seen. Rainbow flashes of light can be seen in normal diamonds, but those in filled diamonds look different from those in normal stones, so some experience in looking at diamonds is useful.

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