Bangkok Gems & Jewellery Magazine


			Old issues	Vol. 18 No. 5 -- December 2004
				Synthetic Diamonds
				The Art of Culturing Pearl

Synthetic Diamonds

Synthetic diamonds have been quite a bit in the news lately, and why not? With the difficulty to distinguish between the natural and the manmade that was initially giving the diamond trade ,not to mention De Beers,sleepless nights,the industry probably thought that it had its hands full with Apollo and Gemesis. However,it has recently comt to light that the Russains are busy bettering the technology that they sold to Gemesis, guaranteeing a further nightmare for the industry.Walther Barshai reports on the latest in Russian diamond synthesizing technology.

Although I always enjoy trips to my former motherland (Russia), this time it was a hectic experience, non-stop talks and nerve-wracking negotiations. As usual, Akademgorodok, the centre of Russian science, was bristling with life. Young and old, everybody looked like Einstein, or at least, a very close replica. Thick glasses resting on some nose bridges. Uncombed hair streaming up with thoughts of great achievements, reaching for the grey autumn Siberian sky.
Turtleneck sweaters of the 60's. Everything reminded me of human potential and high regard for achievement and disregard for personal appearance or well-being. Some of course, and in particular the burocratchiks, looked quite different - tidy neckties, clean shirts, ironed trousers. This combination of the two makes this modern world wonder so distinct and without precedent.

    Among other things, I visited Professor Yuri Nikolaevich Pal'yanov, whom I met about 10 years back when his research into synthetic diamonds was in its infancy. He, as always, pleasant and polite, stunned me with the advancement of his technique. The old small (hardly ° carat in size), brownish stones with black metal inclusions are all but gone and now are replaced with fancy-yellow beauties up to 6 carats in rough. I was also lucky enough to examine some white and light blue specimens.
     Besides jewellery applications, these stones have an even wider range of technological and scientific use. X-ray equipment, radiation detection, electronic applications are just a few examples.
    It is known that natural diamonds are formed at pressures of 5-6 GPa and temperatures in the range of 900-1400°C. Until recently diamond crystallisation ander such conditions could be realised only in metallic systems, which are unlikely to correspond to the natural diamond formation environment. Dr. Pal'yanov's team has also found that the diamonds can be crystallised in alkaline carbonate-fluid melts at temperatures and pressures similar to those of natural diamond formations.     The system Dr. Pal'yanov uses is known as the "Split Sphere".   The process utilises Na2CO3, K2CO3, graphite and oxalic acid dehydrates, generating C-O-H fluid. Further, he added minute diamond particles as seeds to the charge. Crystallisation process is done in sealed platinum ampoules. Considering the abundance of carbonates in diamond-breaking rocks of magmatic and metamorphic origin, as well as the aqueous carbonaceous composition of mantle fluid, Dr. Pal'yanov's team suggested that alkaline carbonate-fluid melts represent the most likely medium for natural diamond formation.
       Having finished the contract with Gemesis Corporation in Florida, Dr. Pal'yanov and his team continued production and research on synthetic diamonds. At present the main areas of their activity are improving the quality and colour characteristics of synthetic diamonds, growth and modification of diamonds for high technology applications and modelling natural diamond formation processes. Dr. Pal'yanov notices several obstacles, but his youthful enthusiasm left me with no doubt about the success of his endeavour.
        The synthetic diamond is a definite threat to the De Beers cartel. The comparison can be made with other Created Gems, but there is no gem that is being monopolised to the extent that the diamond is. The price of natural stones is artificially inflated, not like some other gems that are freely traded by miners and brokers. The scarcity of man-made diamonds still commands a high price, somewhere in the range of 75-90% of its natural counterparts. The main difference between a "Created" and a natural stone is that one is made and the others is found.
Properties of Natural and Synthetic Diamonds
Hardness =10
Refractive index = 2.42 (off the scale for
most gem refractometers).
Dispersion = 0.044
Internal inclusions such as feathers,
clouds, veils, pinpoints, etc.
      Thermal conductivity (standard test used to differentiate diamonds from other colourless, high refractive gemstones, such as cubic zirconia). Natural Diamonds: Positive Identification Features Included crystals (also known as "carbon spots"). Indented trigons (natural triangular shaped external features on diamond crystals). Note: raised trigons may be associated with either natural or synthetics. Blue fluorescence.   Occurs in all colours, including colourless. Note: expect this to change as soon as the synthetic diamond technology matures! Mottled zoning that does not repeat every 90°. Usually octahedral crystal habit (uncut). Synthetic Diamonds: Positive Identification Features Metallic inclusions. Hourglass-shaped and columnar internal colour zoning. Repeats every 90° of rotation. Radiating octagonal surface pattern on table (raised external feature that remains after polishing). Geometric patterns (e.g. crosses) seen in fluorescence due to zoning of light emitting ions. Fluorescent pattern is usually green or yellowish green, sometimes orange, but never blue. Phosphorescence (up to 30 seconds) in near colourless stones. Cube octahedral crystals (uncut).

THE ART OF CULTURING PEARLS

A Delicate Operation With Uncertain Results

There is a rather pathetic joke that asks, "How do you culture a pearl, sing to it? No, Irritate it!" As jokes go, this one is truly pathetic but it serves to illustrate the principle behind the creation of a pearl. Be it natural or cultured, the genesis of all pearls is the introduction of an irritant into the soft tissues of an oyster's body. This irritant could be a microscopic bit of food or other organic matter or some parasite that has lodged itself in the soft inner body of the oyster from where it cannot be expelled. The oyster's defensive reaction against this unwelcome intrusion is to coat the offending particle with layer upon layer of nacre and the result is the softly glowing gem we call a pearl. The nacre is not just a soothing substance. Nacre is a smooth hard crystalline substance that is made up of alternating layers of aragonite and conchiolin. It is composed of microscopic crystals, each crystal arranged in perfect alignment with the others so that light passing through the axis of one is reflected and refracted by the other to produce a rainbow of light and colour. Pearls are unique in that they are the only gems produced inside the body of a living organism and moreover, they are also the only gems that are ready to use when found, there is no need to cut, or polish or shape or facet it. Just drill a hole and it is ready to be used.
Natural pearls are wholly created by nature, whereas in the case of cultured pearls, man jumpstarts the process by surgically implanting" the irritant inside the oyster. From there on nature takes over and the remaining steps of secreting the layers of nacre to make a pearl are left to nature.
The modern grafting technique, which is derived from the Mise-Nishikawa method, varies a little from farm to farm, but it basically follows a series of common steps. First the oysters are cleaned and scrubbed. They are packed into trays with a little saltwater. When the oysters gape open, a small

A.Opening an oyster to find a perfect pearl.If all goes well with the culturing process there is a 5% chance that the resulting pearl will be a perfect specimen.
B.Pearl Oyster.

C.Freshwater mussels can yeild more than one pearl at a time and they can be reused again.
D.Cage of oysters are line up in shettered bays for cultivation.
E.Implanting a bead nucleas to jumpstart the oyster's nacre production.



	A foreign object having strayed into the oyster between the shell and the mantle lobe.				Pearl layers (shell) Mantle lobe outer epithelium Mantle lobe inner epithelium

	The foreign object (nucleus) being gradually implanted in the mantle lobe.

	The nucleus closing up inside the mantle lobe and the cell in a pearl-sac secreting nacreous substances

wooden wedge or speculum is inserted between the valves to keep the animal from closing them.
Then they are taken to the pearl technician who makes a small incision near the oyster's foot. He then inserts a small probe like tool to make a tunnel, guiding it around delicate organs. This is an incredibly delicate operation. If the technician makes even the slightest mistake, the oyster will die. After making the tunnel, the pearl technician uses a cup like tool called the nucleus holder to insert a spherical nucleus made out of the mother of pearl from the shell of the Mississippi freshwater mussel. This nucleus is the core around which the oyster will make its pearl.Just the nucleus however, is not enough to get the oyster going about its work. The technician also inserts a small piece of the mantle tissue the mantle is a skin like organ that secretes the mother of pearl).This piece of mantle tissue will graft itself onto the surrounding tissues and then it will produce a man induced pearl sac.
The nucleated oysters are then returned to the sea, where they live in sheltered bays rich in natural nutrients. The nucleated oysters are suspended from pearl rafts in order to give them best conditions for growth. Pearl technicians constantly monitor the water temperature and feeding conditions daily at various depths and move the oysters up or down according to the best growing conditions.
From time to time, the oysters

F.Examining and cleaning the oysters from time is neccessary to prevent disease.
G.Harvesting of pearls.
H.Bead nucleus of different size yield pearls of corresponding sizes.Smaller beads pose lesser risk while a bigger one will produce a larger piece but with a greater risk of oyster mortality.

are lifted out from the sea for cleaning and health treatments. Seaweed, barnacles and other undersea growths that might impede their feeding are removed from the shells which are then treated with medicinal compounds to prevent parasites from hurting the oysters in any way.
There are nevertheless, many hazardous factors that cannot be controlled by man. Natural disasters like typhoons, attacks from predators and even the suffocating
red tides are all fatal to the oysters. However, those oysters that survive these natural hazards are finally harvested for their pearls.
Every year, millions of oysters are nucleated but only a fraction of that number survives and even fewer actually bear a pearl. Of all the oysters that yield a pearl, only a fraction bear one of gem quality and of these, only a few bear a perfectly round pearl. Therefore it must be understood that although man may start the process of pearl production

i. Assorting pearls by size,shape,colour,and luster.It may take as many as 10,000 pearls pearls to yeild enough matching pearls make a single necklace.

by inserting the irritant that forms the core of the pearl, nevertheless after this preliminary interference, everything else is left to the whims of nature. Therefore even cultured pearls are real jewels.Like natural pearls, no two cultured pearls are ever identical. Therefore sorting pearls calls for refined skills that blend similar looking pearls together so that they match. When it comes to drilling, a great deal of care and precision is required as a hole drilled even fractionally of centre can rum the pearl for use in a necklace or jewel that depends upon the symmetrical assembly of its pearls. Because no two cultured pearls are alike, assorters go through about ten thousand pearls before they find enough similar to make a single necklace. Therefore cultured pearls are truly precious and here it is pertinent to point out that all marine pearls in the market today, be they akoya. South Sea, Tahitian or mabe, they are all cultured and cultivated on pearl farms.