• Irradiation
• HPHT
• Coating

When these processes are performed professionally, and accurately, these diamonds are absolutely safe for the jewelry industry use.

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Irradiation
The highly common process practiced for color enhancement is called irradiation.
This process uses high-energy electron saturation (electron accelerator technology) to alter the appearance and color of diamonds.

With this process and varying degrees of irradiation, jewelers are able to transform natural colorless diamonds into brilliant stones featuring hues
such as canary yellow, pink, blue, gold, green, cognac, orange and black.

Different levels of heat combined with various shaped diamonds allow the jeweler to masterfully create beautifully colored works of art. The process of irradiation is flawless and can only be detected with spectroscopy. The result is a beautiful, permanent, radiation-free colored diamond.


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HPHT (High Pressure High Temperature)
As a natural attribute, the verity of colors presented in diamonds, are the result of structural irregularities formatted at the atomic level, causing the different elements trapped in the diamond to reflect its color. Presence of nitrogen in the diamond would result in a yellow overtone, and boron traces wouldreflect a blue color to the diamond.

The core of the process imitates and executes the natural conditions of High Pressure and High Heat, which exists in nature during the formation of diamonds at their primary state. Those conditions are responsible for the creation of the diamond through its characteristics (i.e. color, size, etc.).

By creating natural elements of Heat and Pressure, and in turn exposing the diamond to those extreme conditions, an alteration in color is resulted,
due to structural changes in the diamond matrix. The resulted color is subject to the original color of the diamond, which is defined as one of the 2
types: Type l or Type ll.

Type l diamonds represent approximately 95% of all diamonds in nature. They are typified by moderate to high levels of nitrogen content, which is responsible for the yellow color and overtone in the diamonds. By applying the process to Type l diamonds, the coloration can change from cape colors (yellow colors) to orange, green and intense yellow colors.

Type ll diamonds represent approximately 5% of all diamonds in nature. They are typified by very low levels of nitrogen content. Structural disorders in Type ll diamonds are responsible for the brown or bronze colors and some times even a light orange hue, in the diamonds. By applying the process to
Type ll diamonds, the coloration can change from their shades of brown and bronze, to colorless, near colorless, pink and blue.

A point to regard, is the mere fact that only diamonds with very high clarity grade can sustain the HPHT process, whereas, any feather or other formed inclusion in the diamond can fail to absorb the very high pressure applied on the diamond, hence causing it to crack.

HPHT diamonds require no special attention in daily use.


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Coating
The irradiation process and HPHT treatment are used for producing many colors, except pink. By using those processes, the resulted pink color is
not pure, and usually accompanied with purplish undertones.

Leshem is using the most updated technique for coating its diamonds in order to produce the purest, clearest, natural looking pink color.

In the past, the coating techniques were unsophisticated; therefore, the pink colored diamonds were not easily integrated in jewelry designs due to
their low durability. Today, the pink coloration of our diamonds result in a fine film coating line at the pavilion facet junctions, which distributes the
color evenly throughout the diamond. The sophisticated film coating technique enables us to produce pink color looking diamonds at any quantity,
with the distinct notions of esthetic and durability. A beneficial factor of using the coating technique is the advantage of reversing and re-doing the process relatively easily.

© 2009 Leshem Diamonds USA