High Pressure High Temperature Treatment
Continuous developments in technology have created different treatment techniques used to improve the appearance of diamonds.  The colour of particular types of diamond can be altered artificially by subjecting them to conditions of extreme heat and pressure. The colour of a diamond following HPHT- treatment is dependent on the exact conditions used and the diamond type. The HPHT process is perfectly acceptable so long as it is disclosed to the purchaser.

Scientists divide diamonds into various types. The vast majority (over 97%) of diamonds handled by the jewellery industry are called Type I. A tiny minority of diamonds (approx. 2%) are called Type II.

These two types can then be further classified into Type Ia and Ib, and Type IIa and IIb.

HPHT deals with Type IIa diamonds which have no nitrogen and are colourless. These Type IIa diamonds due to  crystal lattice defects sometime show brown colour. Putting the diamond under high pressure and high temperature results in a repaired crystal lattice, and a colourless diamond.

In Type Ia diamonds the HPHT process causes dispersion of paired nitrogen into single nitrogen molecules and cause the diamond to take on a colour of fancy yellow to yellow-green. This transforms a unsaleable poor coloured diamond into a valuable fancy coloured diamond.

HPHT- treated diamonds are impossible for gemmologists to identify using standard gem testing instruments and therefore, undisclosed HPHT- treated diamonds are a great concern to the gem and jewellery industry. However, AnchorCert has invested in the latestest technology which can help identifiy HPHT-treated diamonds. All diamonds submitted to AnchorCert are screened and examined to ensure they are natural. If a diamond shows signs of having been exposed to treatment, further tests would be carried out to identify if the stone had been subject to HPHT treatment. AnchorCert are the only UK diamond grading authority equipped to identify this.

CVD - Chemical Vapour Deposition
Chemical vapour deposition, developed in the mid 1980’s is a process by which incredibly thin films of diamond a few microns thick can be generated and deposited on a base.  The process involves high temperatures (over 2000°C) and lower pressures than involved in HPHT. Mixtures of hydrogen and hydrocarbon gases are energised with heat or electrical energy in a deposition reactor. The carbon molecules are deposited on a substrate as a thin film of polycrystalline material. 

Quality and purity are very high and particular diamond properties can be selected.  Boron added to the growth gases, for example, will produce an electrically conducting diamond.  When the diamond layer has reached the correct thickness the reactor is shut down and the CVD wafers can be removed. Single crystal diamonds can also be grown, but sizeable gem quality is proving difficult. All CVD diamonds are believed to be Type IIa diamonds as no nitrogen is present.

CONFLICT DIAMONDS - THE FACTS
Environmental and Humanitarian Issues are of increasing concern to the consumer.  Many are now seeking reassurance that the goods they are buying have been produced in a responsible manner and that the people involved in the supply chain have not suffered in any way.

This is of particular concern to many when buying high value luxury items as an expression of love and commitment.
It is true that in the past “conflict diamonds” have been a source of revenue which has funded civil conflict in countries such as Sierra Leone and Angola. This problem was recognised in 1998, following a decade of violent conflict in the continent of Africa. Concern from non government organisations such as Global Witness and the jewellery trade itself resulted in a United Nations resolution in 2000 and the establishment of the Kimberley Process in 2002.  The Kimberley Process has been adopted by 68 governments worldwide and regulates all rough diamonds. It is now estimated that only 1% of the annual production of diamonds are traded outside the Kimberley Process. All responsible UK retailers will require that diamonds have a Kimberley certificate to ensure that they are not conflict.

For more details visit www.kimberleyprocess.com

The mining of diamonds and gold employs millions of people in the world’s poorest areas, particularly in Africa, and in India a further 700,000 are employed in the diamond cutting industry. It is crucial to the survival of these people who in most cases have no alternative source of employment or income.
The Western consumer spend on gold and diamonds is keeping millions alive. If this spend should fall for whatever reason it would have severe consequences for many communities and cause untold suffering for the people of Africa and their families This particularly applies to those in areas where long term conflict has devastated the economy and the population are struggling to recover and survive..

The facts are:

• The Diamond  industry alone employs 10 million people globally
• As two of its major resources diamonds & gold are helping transform Africa & the lives of its people
• Income from diamonds and gold make a difference in the developing world by providing jobs, roads, healthcare, education
• The Kimberley Process has significantly reduced the amount of conflict diamonds in circulation
• Major players at every stage of gold an diamond supply chain have committed to taking a more responsible approach

For more information visit www.diamondfacts.org or www.responsiblejewellery.com

Cobalt Coated Tanzanites
AnchorCert detected examples of tanzanites which had been enhanced by the latest process – cobalt coating. The treatment takes the form of a surface coating which can improve the apparent colour of the tanzanite by as much as two grades, ie from A or AA to AAA or AAAA. The colour enhancement makes the stone apparently better quality, and therefore more valuable, than it was originally. However, the cobalt can be polished off and the treatment should definitely be disclosed by the seller.

The treated stones detected by AnchorCert were between 30 points and one carat and the supplier knew that the stones would be submitted for certification. This suggests that some of the supply chain is buying and selling in good faith and is not yet aware of the new treatment, which only became available commercially within the last 12 months. The cobalt treatment is sometimes quite hard to identify with a 10x loupe, but under higher magnification, using a gemmological microscope there are give away signs. AnchorCert gemologists automatically look for the signs and if the coating is in any way imperfect they are easy to spot.

On a perfect example the only way you can tell with the naked eye is by the colour, which just doesn’t look right. When checked with a loupe you can see that the colour is patchy, particularly when viewed from the crown, and when the stone is put under X –Ray Fluorescence it will show relatively high levels of cobalt.