Archives

By Prof. P. G. R. Dharmaratne, Chairman, National Gem and Jewellery Authority

Ruby and Sapphires of all colours are the varieties of gems in the corundum species of minerals. Basically corundum is composed of Aluminium Oxide (Al2O3) and it has no colour but when Chromium (Cr) is present it produces red colour which is called Ruby.

Any other colour of corundum is called Sapphire with the prefix for colour. Blue Sapphire is produced when Titanium and Iron are present in very small quantities as impurities or Iron alone causes yellow colour in corundum. There are also other colours such as green, brown, orange, violet and reddish orange (Pathmaraga).

Earliest sources

Sri Lanka is considered one of the earliest sources of ruby and Sapphires. The earliest mention is made in the Mahawansa that Lord Buddha visited Sri Lanka in 500 BC to resolve a dispute between two tribal kings, which arose due to a gem studded throne. Since then many ancient travellers to the east and Fareast such as Pa-Hein, the Chinese monk, Marco Polo and Travenier have made graphic accounts of the magnificent gems they saw in Ceylon.

It is also believed that the valley of Rubies mentioned by Sinbad the traveller in the stories of Arabian nights is Ceylon. The legend also is that king Solomon wooed the heart of Queen Sheeba with Sapphires from Ceylon. Although many historical references exists about Rubies of Ceylon, today we are not known as a Ruby producing country but our reputation as a Sapphire producer, particularly blue, yellow and pathmaraga has never diminished. Many tons of Sapphires are produced in the world, mainly in Sri Lanka, Madagascar, Australia and Tanzania.

Synthetics

In 1902, when Auguste Vernuil of the Paris Academy of Science introduced new Rubies and Sapphires, they caused sensation in the trade. He said his products are 'equal to nature's finest'. Since gem and jewellery dealers and customers had no way of differentiating the natural from synthetics, prices plummeted.

Within five years millions of carats of synthetic Rubies and Sapphires were put out to the market and the sudden influx relegated synthetics to low-priced commodities, and it took years for the naturals to return to prices that accurately reflected their rarity.

Although synthetics too have all three traditional criteria required to be called gems; beauty (with coloured stones it means the intensity of colour), durability and rarity, they lack one other important thing, the naturalness which makes them rare. So finally naturalness restored the glorious position of Ruby and Sapphire. The availability of inexpensive, uniform material in synthetics resulted in the production of jewel watch bearings to reduce wear and frictions.

Then in 1930, new synthetics were introduced by Chatham of USA, where gems are grown as crystals within a pure platinum crucible in which ingredients to make Ruby or Sapphire are dissolved at around 1200 C and the solution resembles earth's molten magma. When the furnace cools after 6 - 7 months, synthetics crystals of ruby or Sapphire resembling naturals have grown.

While Vernuil synthetics cost around a dollar a carat, this new synthetics cost much more, and in fact it's about several hundred dollars. They were much superior to those of Vernuil synthetics but the threat to naturals again lasted only for a short period. The Czochralski made synthetics in another way where, form a solution of ingredients necessary to produce Ruby and Sapphire, a slowly rotating natural seed crystal was pulled out and the condition was such that a new synthetic rod grew at the bottom, perfect for producing lasers.

Synthetic produced in several hundred tons and in very clear form than the natural and at a fraction of the cost of the natural, today we find its uses not only in costume jewellery but in various other ways. Radiation, either from the sun or from atomic blasts, sometimes causes errors in microchips.

When stray charged particles penetrate circuits, they travel through traditional silicon substrates, upsetting normal readings. The Sapphire is an almost perfect insulator, naturally "radiation hardens" circuits. Over the past few years, manufacturers have replaced traditional silicon on silicon chips with silicon on Sapphire (SOS) in military and communication satellites, and in microcircuit for missiles, fighter plans, tank and battlefield installations. Supermarket checkout counters need hard, clean windows for sweeping lasers over windows and synthetic Sapphire provides the best answer as it last over eight years as against glass windows which are prone to ware and tare in a few months.

Similarly, continued transparency is necessary for missiles censors to work effectively. During months of training flights, airborne sand and other debris abrade traditional missile windows but the Czochrolaski pulled synthetic single crystal Sapphire dome in the nose of a heat-seeking missile protects its censors from such hazards. It is strategically unsound to defend US$ 30 million airplane or billion dollar missile blinded by scratches on its nose. Hair - thin Sapphire reinforcing fibres for the supersonic aerospace plane, tiny Sapphire tubes incorporated into automatic blood sampling machine (because blood wont coagulate on single crystal Sapphires) and surgical tips for medical lasers are some other instances where synthetic Sapphires are used.

So much of uses for clean synthetics Sapphires, but the trade enjoyed the value of naturalness, good lustre and bright colours of Sapphires for a while until Australia came out with dark inky natural blue Sapphires in quantities with the ability of finding matching stones for a bracelet or a necklace much easily at a low cost. It went into the extent of the trade believing that you do not need bright lustrous blue in Sapphires. Even today look at all those necklaces and bracelets with Sapphires advertised in airline magazines, they do not look blue but rather black. To an ignorant customer, they are Sapphires alright but, only if he has not seen real Sapphires like those of Sri Lanka. Bulk diffusion of Sapphires

During the 1980's disaster struck Sapphires once again, in the form of diffusion where colour causing elements were introduced into colourless Sapphires at temperatures around 1700 C to a thin surface layer (a fraction of a millimetre) which produced a colour layers corresponding to those elements. Although uniform brightly coloured rubies and Sapphires were produced this way and started mixing with natural ones or even selling as they are at a much lower price than the natural stones of similar colour, identification of such stones was easy so that effect of diffusion treated stones did not last long either. Perhaps, the biggest threat to the Sapphire has just hit the industry with what is known as "bulk diffusion of Sapphires". Orange and reddish orange (Pathmaraga) Sapphires are very rare in nature. May be you will find one such stone along many thousands of stones found in a year. A few months ago, an unusually large quantity of such stones appeared in the market, particularly in Thailand.

Japan, the largest consumer of such stones went on buying and passing into customers until the suspicion arose due to an excessive quantity were in circulation. The tests on those proved them to be diffusion treated but the element responsible for the change was hither to an unknown colour causing element, beryllium. (The usual elements causing colour in gemstones are Cr, Fe, Ti, Mn, Co, Cu and Ni).

It was found that unlike previously known diffusion treated stones, colour change has occurred to a much deeper level, sometimes throughout the stone so it got the name bulk diffusion. It was also found out that cost of testing is over US$ 300 and it needs not only basic gemmology equipment, but also expensive analytical equipment. When Japan came to know of this the dealers recalled over 20,000 stones from customers, which have been earlier certified and sold as only heat treated and re-tested and certified as diffused stones. Since then Japan has stopped purchasing orange Sapphires and Pathmaraga. This has seriously affected the gem and jewellery trade. According to Thai gem traders, this change of colour took place during normal heat treatment which are accepted by the trade. They state that the presence of chrysoberyl of same colour, with yellow Sapphires in the same crucible during the heat treatment has due to misdiagnosis, caused this colour change. Subsequently, traders seem to have purposely treated yellow Sapphires with chrysoberyl to change colours of natural yellow Sapphires this way.

They maintain that since they use natural chrysoberyl, they do not accept this as diffusion, but consider only as a heat treatment - a fact international trade do not accept. They support their argument by the fact that during normal heat treatment - light elements such as oxygen, hydrogen which are not colour causing element my diffuse into the stone but it is called "heated only" while diffusion of beryllium, which is also not a colour causing element should not be called diffused. Worse is yet to come. At the International Coloured Gemstones Association Congress (ICA) held in India in January 2003, it was revealed by Shane McClare, a Gemmologist from the Gemmological Institute of America (GIA) that not only orange and reddish orange but other colours such as blue, green and brown coloured Sapphires are also produced by the same beryllium bulk diffusion treatment. This is alarming as every coloured Sapphire may require a certificate declaring whether the stone is heated only or treated.

While normal heat-treated stones are accepted world-wide as an enhancement, diffused stones are required to be called 'treated'.

The term 'treated' is used for diffused or coated stones or stones treated with coloured oil or wax to hide the cracks of the gemstones. Natural untreated, natural but heated and diffused stones fetch prices in decreasing order. Therefore, it is essential that Sri Lanka should acquire the expertise and the equipment to be able to certify a stone. This is particularly important since over 75% of gem exports by value are Sapphires of various colours, particularly blue and yellow.

MoU

On this aspect, it is noteworthy that the Prof. G. L. Peiris, Minister of Enterprise Development, Industrial Policy, Investment Promotion and Constitutional Affairs has already signed an MoU with the American Gem Traders Association (AGTA) to establish a fully equipped gemmology laboratory in Sri Lanka which will be able to issue internationally acceptable certificates for gemstones. The recruitment of staff for the laboratory is being attended to at present. The NGJA has also registered all the heat treaters in the country to ensure that they strictly adhere to the conventional heat treatment only. So far we have not come across any heat treater engaged in bulk diffusion.

News | Business | Features | Editorial | Security
Politics | World | Letters | Sports | Obituaries |

Produced by Lake House
Copyright 2001 The Associated Newspapers of Ceylon Ltd.
Comments and suggestions to :Web Manager