What can infrared spectroscopy do for you ?

Diamond Detection
One of the traditional techniques used to differentiate diamonds from imitations and other precious stones is Fourier Transform Infrared (FT-IR) Absorption Spectroscopy. This technique is well known to generate molecular information, directly related to the chemical structure and composition of a stone. It is also used to classify the different types of diamonds based on impurities (nitrogen and boron).

Type Screening
The importance of diamond types. The type of a diamond provides valuable information on its history. This may refer to the geologic conditions to which natural diamonds have been exposed in the earth or to the laboratory conditions during treatment or synthesis. As the detection of diamond treatments and synthetics requires advanced testing equipment in well-equipped gem testing labs, a better understanding of how the diamond type relates to a natural or treated colour on one hand and synthetic diamond growth on the other hand, optimizing the screening process. In recent years, the production and the quality of synthetic gem diamonds have increased dramatically. In particular, significant developments in the chemical vapour deposition (CVD) method have allowed the introduction of high quality (near-)colourless and good clarity CVD diamonds in the gem market. Synthetic diamonds produced with the CVD method are most commonly type Iia.

Synthetic diamonds can also be grown with the High Pressure High Temperature (HPHT) method. All known colourless to near-colourless CVD or HPHT synthetic diamonds are type IIa. It is also well known that brownish type II diamonds can be subjected to a HPHT treatment to reduce or remove the brown colour component, making them appear colourless. Note that natural type IaB diamonds are also be potentially subjected to HPHT treatment to enhance the colour.

Type I Diamonds
Diamonds containing nitrogen (Type I diamonds) are estimated to have an abundance of roughly 98% in the natural diamond populations worldwide. Type I diamonds are divided into type Ia and type Ib, depending on how the nitrogen impurities are arranged. When the nitrogen atoms are grouped in aggregates, the diamonds are referred to as type Ia diamonds. When the nitrogen atoms remain isolated, the diamonds are of type Ib.

Type II diamonds
Type II diamonds are considered as the purest form of diamond from an atomic point of view. Type II diamonds are subdivided into types IIa and IIb. Type IIa diamonds do not contain any detectable nitrogen or boron using FT-IR methods. This group is very rare in nature (approximately 1% to 2% of all diamonds). Type IIb diamonds (< 0.1% of all diamonds) have substitutional boron atoms in the crystal lattice. As a result, these diamonds are blue, although they can also be brown and grey to near-colourless.

Therefore, the identification of the diamond type is critical in screening. With the increasing availability and complexity of treated and synthetic diamonds, all stakeholders, from diamond mining to diamond sorting, diamond traders and gem certification laboratories, will benefit from an adequate identification of the diamond type, enhancing consumer confidence.

Benefits Of The Alpha Diamond Analyzer

• High customer confidence by reliable diamond detection and type screening
• Selection of possibly HPHT treated or synthetic colorless diamonds
• Reliable sorting and valuing of polished diamonds
• Automated diamond detection and type classification
• Reliable results within a minute
• Reliable detection of common diamond imitates
• Wide range of shapes and sizes
• Easy to use

For more information:
HRD Antwerp | Hoveniersstraat 22 | BE-2018 Antwerp | Belgium
T. +32 222 06 23 equipment@hrdantwerp.be
www.hrdantwerp.be