Ceylon GEM page

Silver

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Silver usually occurs in massive form as muggets or grains, although it may also be found in wiry, dendritic (tree-like) aggregates. When newly mined or recently polished, it has a characteristic bright, silver-white colour and metallic lustre. However, on exposure to oxygen in the air a black layer of silver oxide readily forms, tarnishing the surface. Because of this, and the fact that it is too soft to be used in most jewellery in its pure form, silver is often alloyed with other metals, or given a covering layer of gold. Electrum, an alloy of gold and silver in use since the time of the Ancient Greeks. contains 20-25 per cent silver. Sterling silver contains 92% per cent or more pure silver (and usually some copper), and Britannia silver has a silver content of 95 per cent or more. Both alloys are used as standards to define silver content

. OCCURRENCE - Most silver is a by- product of lead mining, and is often associated with copper. The main silver mining areas of the world are South America, the USA, Australia, and the former USSR. The greatest single producer of silver is probably Mexico, where silver has been mined from about AD1500 to the present day. The finest native silver, which occurs naturally in the shape of twisted wire, is from Kongsberg, Norway.

-Silver wine cup-

This part gilt silver cup was fashioned in 1493,when the silver was valued as height as gold.

Gold

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Gold

The color of gold depends upon the amount and type of impurities it contains. Native gold is typically golden yellow, but in order to vary its color and increase its hardness for use in jewellery, gold may be alloyed to other metals. Silver, platinum, nickel, or zinc may be added to give a pale or white gold. Copper is added for red or pink gold; iron for a tinge of blue. Gold purity is defined by the proportion of pure gold metal present, and this is expressed as its carat (ct) value. The purity of gold used in jewellery varies from 9 carat (37% per cent or more pure gold), through 14, 18, and 22 carat, to 24 carat, which is pure gold. In many countries, gold is "hallmarked" to indicate its degree of purity.

• OCCURRENCE Gold is found in igneous rocks and in associated quartz veins, often in small quantities invisible to the naked eye. It is also concentrated in secondary "placer" deposits - as nuggets or grains in river sands and gravels. Gold may still be extracted from placer deposits by the traditional panning method, but modern commercial mining involves large earth-moving machinery and concentrated acids for processing the ore. The main gold-bearing rocks occur in Africa, California and Alaska (USA), Canada, the former USSR, South America, and Australia.

• REMARK Gold has been used for coins, decoration, and jewellery for thousands of years. It is attractive, easily worked, and wears well.

gold grains

IMITATION AND ENHANCEMENT

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IMITATION gems have the appearance Lot their natural counterparts, but their physical properties are different. They are made to deceive. Man-made materials, such as glass and synthetic spinel, have been used to imitate many different also be modified to resemble more valuable gems. It is possible to enhance authentic gemstones by hiding cracks and flaws, or by heat-treating or irradiating to improve their color.

GLASS IMITATIONS

Glass has been used for centuries to imitate gemstones. It can be made either transparent or opaque, in almost any color, and, like many gems, has a vitreous lustre. At first sight, therefore, it may easily be mistaken for the real thing. However, it can usually be detected by its warmer feel, and by the evidence of wear and tear that results from its greater softness. Chipped facets and internal swirls and bubbles are common. In addition, unlike most of the gems it imitates, glass is singly refractive.

Opal Imitations

Gemmologists call the flashes of color in opal its "play of color", or iridescence. It is caused by the interference of light from the minute spheres of silica gel that make up the gem. This structure is imitated to great effect in opals made by the French manufacturer, Gilson, although the difference can be seen in the mosaic-like margins of the patches of color. There are various other opal imitations, including stones made of polystyrene latex, or of different pieces assembled as one. In an opal “doublet" (two pieces) the top is natural precious opal, but the base is common (potch) opal, glass, or chalcedony. A "triplet" (three pieces) has an additional protective dome of rock crystal.

SLOCUM STONES

The American John Slocum developed imitation opals with a convincing play of color, but they lack the silky, flat color patches of genuine opal, and the structure looks crumpled when magnified.

GARNET-TOPPED DOUBLET

One of the most common "composite" stones (stones made of more than one piece) is the garnet-topped doublet, or GTD. A thin section of natural garnet is cemented to a colored glass base, which gives the GTD its apparent color. The deception is most easily seen at the junction of the two layers, which may be obvious.

DIAMOND IMITATIONS

Many natural materials have been used to imitate diamond, but zircon is the most convincing. Synthetic imitations are popular, but each has its faults (right). Imitations can usually be detected by testing the heat conductivity of the stone.

HEAT TREATMENT

Heating may enhance or change the color or clarity of some gems. Techniques range from throwing gems in a fire to "cook", to use of sophisticated equipment. The outcome is certain for some gems (like aquamarine, changing from green to blue), but less so for others.

STAINING

Stains, dyes, or chemicals can alter the appearance of a gem, coating just the surface, or changing the whole specimen. For staining to be effective, a stone must be porous or contain cracks and flaws through which the color can enter. Porous white how lite, for ex- ample, can be stained to imitate turquoise.

OILING

Oils may enhance a gem's color and disguise fissures and blemishes. It is common to oil emeralds in order to fill their natural cracks and flaws.

Synthetic Gemstone

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SYNTHETIC GEMSTONES

SYNTHETIC GEMSTONES are made in laboratories or factories, not in rocks. They have virtually the same chemical composition and crystal structure as natural gemstones, so their optical and physical properties are very similar. However, they can usually be identified by the differences in their inclusions. Many gems have been synthesized in the laboratory, but only a few are produced commercially-generally for industrial and scientific purposes.

MAKING A SYNTHETIC

Man has tried to replicate gemstones for thousands of years, but it was not until the late 1800s that any substantial success was achieved. In 1877 French chemist Edmond Frémy grew the first gem-quality crystals of reasonable size (see bottom right), and then around 1900 August Verneuil devised his technique to manufacture ruby. With a few modifications, the Verneuil "flame- fusion" method is still in use today. The powdered ingredients are dropped into a furnace and melt as they fall through a flame hotter than 2,000°C (3,630°F), fusing into liquid drops. These drip on to a pedestal and crystallize. As the pedestal is withdrawn, a long, cylindrical crystal, which is known as a boule, forms.

FLU MELT TENIQUE

Pionred by the French chemise Edmond Frémy, the flux-melt technique is still used to make emeralds. The powdered ingredients are melted and fused in a solvent (flux) in a crucible. The material must be kept at a very high temperature for months, before being left to cool very slowly.

FLAME-FUSION CORUNDUM

Synthetic corundum manufactured by flame-fusion grows as a single mass called a "boule". It has the same inner structure as a natural crystal and can be cut to shape.

SHAPES AND COLORS

Because of the way they are made, synthetic gems may show subtle differences in shape and colour that help to distinguish them from their natural counterparts. For instance, corundum produced by flame-fusion has curved growth lines, rather than straight ones, because the ingredients have not mixed together fully. Some synthetic gems may also suffer from uneven colour distribution. Flame-fusion spinel is manufactured to imitate gems such as ruby, sapphire, aquamarine, blue zircon, tourmaline, peridot, and chrysoberyl.

DISTINCTIVE INCLUSIONS

Synthetic gems have different inclusions from natural gems, so often the best way to tell them apart is to examine them with a loupe (below) or a micro- scope. Synthetic inclusions may be typical of a process, or of a synthetic gem species. For instance, in Verneuil rubies, gas bubbles have well-defined outlines; in flux-melt emeralds (right), characteristic "veil" and "feather" patterns form.

GILSON GEMS

Lapis lazuli, turquoise, and coral produced by the French manufacturer, Gilson, are similar to their natural counterparts, but are not true synthetics because their optical and physical properties differ from the natural gems. Gilson lapis lazuli, for example, is more porous and has a lower specific gravity.

GILSON EMERALD INCLUSIONS

Synthetic emeralds from the French manu- facturer, Gilson, have characteristic veil-like inclusions. The gems are made from poor- quality material by a flux-melt method.

HISTORY AND FOLKLORE

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HISTORY AND FOLKLORE

THERE ARE NUMEROUS myths and legends associated with gems. Some tell of cursed stones; others of stones with special powers of: healing, or that protect or give good luck to the wearer. Some of the largest known diamonds have legends associated with them that have been told and re-told over centuries, and many now lost are surrounded by tales of intrigue and murder. Some mines are thought to be cursed - probably a rumour spread by the mine-owners to keep unwanted prospectors away. In Burma, for instance, where all gemstones belonged to the monarch, the belief that anyone who took a stone from a mine would be cursed may have been deliberately cultivated to curb losses of a valuable national asset.

crystal gazing

Since Greek and Roman times, balls of polished rock crystal have been used to see into the future. The difficulty of finding a flawless piece large enough to be polished adds to the mystique. The mystic gazes at the ball, lets the eyes go out of focus, and then interprets the misty.

DEATH MASK This Aztec funeral mask adorned with turquoise may have speeded entry to the next world.

PERUVIAN GOD

This 12th-century ceremonial knife from Peru is made from gold adorned with turquoise. The handle has been formed into the image of a divinity.

THUMB GUARD

This 17th-century ring. mounted with rubies and emeralds, was protect archers' thumbs when releasing arrows.

BIRTHSTONES

Certain gems have traditionally been associated with different months of the year, and are thought lucky or important for people born under their "influence". This probably stems from the ancient belief that gems came from the heavens. Many eultures associate gems with the signs of the zodiac, and others with the months of the year, but the selection varies from country to country, perhaps influenced by availability of gems, local traditions, or fashions. The custom of wearing birthstone jewellery started in 18th-century Poland, and has since spread throughout the world. The most popular selection today is shown right.

CRYSTAL HEALING

a very long history, as the rituals of medicine men in ancient tribes attest. Crystal healers today believe that each gem has the power to influence the health and well-being of a specific part of the body. The light| reflected off stones placed on vital nerve points is thought to be absorbed by the body, supplying it with healing energy.

ROCK CRYSTAL

Prized for their beauty and clarity, rock crystals are often chosen for use in crystal healing.

CRYSTAL PENDANT

Gems worn close to the skin are believed to heal or protect.

GEMS THROUGH THE AGES

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GEMS THROUGH THE AGES

PEOPLE EVERYWHERE, throughout history, have followed a natural instinct to collect things of beauty and value, and have used whatever gems they found locally - from shells to sapphires to adorn themselves. Today, the whole range of the world's gems is available to those who can afford them There are more gem-producing areas than ever before, new stones are on the market, and jewellery designs continue to evolve. But the inherent attraction of gems their beauty, durability, and rarity - remains the same.

First Uses

Gem materials were probably first used as much for their durability as their beauty. But beauty was not ignored, even then. For example, the Stone Age obsidian axe below has been wrought to be attractive as well as practical, and ancient civilizations did fashion gems purely for adornment. Although most were primitive in design, some were highly intricate, with painted surfaces. Down the ages, gems have also been offered as prestigious gifts, and their portability and intrinsic value gave them a natural use as currency.

EARLY COLLECTORS

The earliest collectors found gems with no more equipment than a stick or shovel, a basket, and a sharp eye. Similar Stone Age tools found in the Mogok area of Burma show that rubies have been mined there for thousands of years - and the same methods of panning the stream with wicker baskets are used today. Evidence of more organized early mining - for example, abandoned mines and waste dumps is found in the Urals of Russia, on the shores of the Mediterranean, in Cornwall, England, and in many other places worldwide.

ANCIENT JEWELLERY

Very little jewellery made before the 18th century services. The best examples are probably those of Ancient Egypt, much of it gold set with gems such as turquoise, lapis lazuli, and carnelian. It shows the great skill of the Egyptian goldsmiths: the gold refined, annealed, and soldered; the probably using silica sand, a technique also known to the Ancient Chinese. The Romans fashioned - went on to develop the polished stone rather than the setting. The art of the goldsmith and lapidary survived in the Dark Ages, though in medieval times gothic style was functional - mainly buckles, clasps, and rings.

UP TO THE PRESENT With the discovery of the Americas in the 15th century, European trade in gemstones expanded, and 16th- ahd 17th-century jewellers could use gems from all over the world. With the rise of an affluent merchant class, jewellery became more widely owned, · and diamonds first became fashionable. In the 20th century, an increase in demand for affordable gems, and the scarcity of the most valuable, will doubtless continue the trend to use more varied gem species in jewellery.

GEM-ENCRUSTED MODERN BROOCH

Jewellery has passed through many styles, from baroque in the 16th century and floral themes in the 17 th, to art deco and beyond in the 20th.

POLISHING CARVING AND ENGRAVING

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PRECIOUS METALS AND GEMS usually I massive, microcrystalline stones and organics-can be worked by polishing, carving, or engraving. Polishing is the oldest form of fashioning. Carving produces three-dimensional objects by cutting them from a larger mass of material. Engraved images are made by scratching out lines or holes, or by cutting away to leave a raised image. Carving and engraving require tools harder than the material being worked.

Polishing

The shine given to the surface of a stone - either by rubbing it with grit or powder, or against another stone - is its polish. Dark- colored gemstones and those that are translucent or opaque, for instance opal and turquoise, are often polished rather than faceted, as are organic gems. They may be polished as beads or as flat pieces to be used in inlay work, or cut en cabochon with a smooth, rounded surface and usually a highly polished domed top and flat base.

Carving

Carving usually refers to the cutting of decorative objects from a larger mass. Stones as hard as 7 on the Mohs' scale were carved in Ancient Egypt, Babylonia, and China. Impure corundum (emery) was used for carving and engraving in India; nowadays a hand-held chisel or turning machine is used. Popular stones for carving include serpentine, Blue John, malachite, azurite, rhodonite, and rhodochrosite

CHINESE CARVING Carving of gemstones in China dates back to the Neolithic period. The most prized material was imported nephrite jade, and decoratice objects like this model pagoda are still made.

Engraving

Engraving usually refers to the decoration of the surface of a gemstone by the excavation (scratching out) of lines, holes, or trenches with a sharp instrument, known as a graver or turin. Of all engraved objects, cameos and intaglios are perhaps the most popular. A cameo is a design (often a human profile) in flat relief, around which the background has been cut away. In an intaglio it is the subject, not the background, that is cut away, creating a negative image that may be used as a seal in clay or wax. Intaglios were particuiarly popular with the Ancient Greeks and Romans, and are still prized by collectors.

GOLD ENGRAVING

The surface of gold and other precious metals used in jewellery may be decorated with intricate patterns, using a hand-held chisel called a graver. Engraved gemstones gained prominence in Europe in the Renaissance period. During the Elizabethan period in Britain cameo portraits were often given as gifts, particulariy among the nobility. All through the ages, layered stones have been used for cameos or intaglios, with onyx and sardonyx particulariy popular. Other gems suitable for engraving include rock crystal, amethyst, citrine, beryl, peridot, garnet, lapis lazuli, and hematite, as well as organic materials such as ivory and jet.

MODERN DESIGNS

This citrine prism, with its clean, architectural lines and exquisite engraving, demonstrates the flair and craftmanship of modern designers. Its maker, Bernd Munsteiner, uses conventional cuts to create classic modern jewels akin to pieces of sculpture. Bernd Munsteiner is one of many artists working in Idar-Oberstein in Germany. Together with Hong Kong, Idar- Oberstein is considered to be one of the most important centres for gemstones today.

Faceting

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FACETING

THE MOST USUAL METHOD of fashion- features, taking into account its color, fashioning a gem is to cut the surface into a clarity, and weight. He may, however, number of flat faces, known as facets. This gives the stone its final shape, or "cut". The craftsman, or lapidary, who cuts the stone aims to show its best have to compromise to retain weight and therefore value. The blue diagrams on the opposite page show the most popular cuts.

How A STONE IS FACETED

There are several stages in the cutting of a gemstone, each of which may be carried out by a different expert. In our example, a rough diamond crystal is fashioned into a brilliant- cut. This is the most popular cut for this stone because it maximizes the gem's naturally strong light dispersion. How- ever, because each stone is a different shape, or has imperfections within it, or because retaining the weight is of paramount importance, the cut in its ideal form (the "make") may not be possible. Nevertheless, the essential aim is to make the diamond bright and "sparkling", showing flashes of color called fire. To this end, the size, umber, and angles of the facets are mathematically calculated. The rough crystal is swan or cleaved to obtain a basic workable piece, then turned on a lathe against another diamond to give it a round shape. The facets are then cut and polished in stages, and the stone is given a final polish before mounting.

BRILLIANT-CUTS

The brilliant-cut is the most popular for diamonds, and for many other stones, particularly colorless ones. It ensures that maxi- mum light is reflected out through the front, giving brightness and fire. Variations in the outline give the oval, the pear- shaped pendeloque, and the boat-shaped marquise or navette.

STEP-CUTS

The step-cut (or trap-cut) shows colored stones to advantage, having a rectangular or square table facet and girdle, with parallel rectangular facets. The corners of fragile gems may be removed, making octagonal stones - as, for example, in most emeralds.

MIXED-CUTS

Mixed-cut stones are usually rounded in outline, with the crowns (above the girdle) cut as brilliants, and the pavilions (below the girdle) step-cut. Sapphires, rubies, and most transparent colored stones are cut in this style.

FANCY-CUTS

These have several possible outlines, such as triangular, kite- shaped, lozenge- shaped, pentagonal, or hexagonal. The cut may be used for rare gems, or to make the most of a flawed or irregularly shaped gem.

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NATURAL INCLUSIONS

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NATURAL INCLUSIONS

INCLUSIONS are internal features of gems. They may be solids, liquids, or gases that the crystal enclosed as it grew, or cleavages, cracks, and fractures that filled (or partly filled) after the host material finished growing. Although usually regarded as flaws, inclusions today are often seen as adding interest to a stone. They can also be invaluable in identifying a gem, because some are peculiar to a particular species, while others occur only in a particular locality.

MICROSCOPE

FORMATION OF INCLUSION

Solid inclusions have usually formed before the host stone - the crystals of the host have grown around them and enclosed them. They may be distinct crystals or amorphous masses. Solids and liquid inclusions formed at the same time as the host are aligned to its atomic structure. For instance, the stars in star rubies and sapphires are caused by needle-like crystals of rutile, which formed parallel to the crystal faces at the same time as the host corundum crystals. Cavities filled or fractures healed after the formation of the host give inclusions that resemble feathers, insect wings, or fingerprints.

DIAMOND WITH GARNET

Solid inclusions may be the same gem type as the host,or different like the garnet in the diamond.

PERIDOT "WATER LILY"

Inclusions that look like water lily leaves are a typical feature of peridot from Arizona, USA. They consist of a central chromite crystal surrounded by liquid droplets.

MOONSTONE "CENTIPEDES"

These insect-like inclusions are a common feature of moonstone. In fact they are parallel cracks caused by strain.

RUTILE NEEDLES

This carved rock crystal perfume bottle contains inclusions of needle-like rutile crystals. Tourmaline and gold are also found in rock crystal.

INSECT IN AMBER

Insects are sometimes found trapped in amber, caught by the sticky resin as it was exuded. Insects have been added to some imitation amber to create a natural effect..

ALMANDINE GARNET

Magnified 45 times, the grey patch on the left is a rounded apatite inclusion. The bright interference colours to the right are due to a zircon crystal.

EMERALD (LEFT)

Rectangular cavities with tails are some- times found in natural Indian emeralds.

Optical Properties

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OPTICAL PROPERTIES

COLOR IS THE MOST OBVIOUS visual feature of a gem, but in fact it is just the optical properties of each gem one of many optical properties, all of which are dependent upon light. The individual crystalline structure of a gemstone interacts with light in a unique way, and determines species. Effects produced by light passing through a gem are described here; those produced by the reflection of light.

What makes color?

The color of a gem depends largely on the way it absorbs light. White light is made up of the colors of the rainbow (spectral colors), and when it strikes a gem some spectral colors are "preferentially absorb- ed". Those that are not absorbed, pass through or are reflected back, giving the gem its color. Each gem in fact has a unique color "fingerprint" (known as its absorption spectrum), but this is only visible when viewed with a spectroscope . To the naked eye, many gems look the same color.

ALLOCHROMATIC GEMS

Allochromatic ("other-colored") gems are colored by trace elements or other impurities that are not an essential part of their chemical composition. Corundum, for example, is colorless when pure, but impurities in it (usually a metal oxide) create the red stones we know as rubies, blue, green, and yellow sapphires, and orange-pink padparadscha. Allochromatic gems are often susceptible to color enhancement or change.

DIOCHROMATIC GEMS

The color of idiochromatic ("self- colored") gems comes from elements that are an essential part of their chemical composition. Thus idiochromatic gems generally have only one color, or show only a narrow range of colors. Peridot, for example, is always green, because the color is derived from one of its essential constituents, iron.

PARTI COLOURED GEMS

A crystal that consists of different-colored parts is called parti-colored. It may be made up of two colors (bicoloured), three (tricoloured), or more. The color may be distributed unevenly within the crystal, or in zones associated with growth. The many different varieties of tourmaline probably show the best examples of parti-coloring, exhibiting as many as 15 different colors or shades within a single crystal.

PLEOCHROIC GEMS

Gems that appear one color from one direction, but exhibit one or more other shades or colors when viewed from different directions, are known as pleochroic. Amor- phous or cubic stones show one color only; tetragonal, hexagonal, or trigonal stones show two colors (dichroic); orthorhombic, mono- clinic, or triclinic stones may show three colors (trichroic).

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CRYSTAL SHAPES

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CRYSTAL SHAPES

MOST MINERAL GEMSTONES are crystalline, with their atoms arranged in regular and symmetrical patterns, like a lattice; a few are amorphous, with no or only a weak crystal structure. Crystalline minerals may consist of a single crystal, or of many in a group. Polycrystalline minerals are made up of many, usually small, crystals; in cryptocrystalline minerals the crystals are too small to see without the aid of a microscope. Crystalline minerals are made up of a number of flat surfaces called faces; the orientation of these faces defines the overall shape, which is known as the "habit". Some minerals have a single, characteristic habit, such as pyramidal or prismatic; others may have several. A lump of crystalline mineral without a definite habit is called massive. Amorphous gem- stones, like obsidian and tektites, have an irregular shape. Examples of common habits are shown right.

CRYSTAL SYSTEMS

Crystals are classified into seven different systems, according to the "minimum symmetry" of their faces. This depends on a crystal's "axes of symmetry"- imaginary lines (shown in black in the artworks on this page) around which a crystal may rotate and still show identical aspects. The number of times the same aspect may be seen - in one 360-degree rotation around an axis - defines that axis as two-fold, three-fold, etc., up to six.

AQUAMARINE

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AQUAMARINE

Aquamarine is a color that is a light bluish tint of green that is in-between cyan and green on the color wheel. It is named after the mineral aquamarine, a gemstone mainly found in granite rocks. The first recorded use of aquamarine as a color name in English was in 1598.Aquamarine’s name comes from the Latin for seawater and it was said to calm waves and keep sailors safe at sea. March’s birthstone was also thought to enhance the happiness of marriages. The best gems combine high clarity with limpid transparency and blue to slightly greenish blue hues. Like many beryls, aquamarine forms large crystals suitable for sizable fashioned gems and carvings

Non-disclosure of this treatment could cause a person to believe that a particular gemstone was of higher quality naturally and therefore be more valuable than it actually is. An added challenge is that treatments can be permanent, long lasting, or short-lived under normal jewelry use. Treated gems may require special care by their owner. In the United States, the Federal Trade Commission has established a set of consumer guidelines outlining the need for treatment disclosures and special care requirements, and countries around the world either adhere to similar guidelines, or have regulations of their own. Additionally there are several professional organizations such as the American Gem Trade Association (AGTA), or the International Colored Gemstone Association (ICA), or The World Jewellery Confederation (CIBJO), that have formulated specific guidelines that their members are required to follow regarding the disclosure of treatments in gem materials. The following glossary includes terms that are often used in the gem treatment nomenclature, and that you may encounter when shopping for gemstones. Finally, treatments for gemstones are constantly being changed and refined, and the detection of these new treated gems is an important part of ongoing gemological research.

The following guide will give a short description of the treatment process, some gems for which the process is used, how easy or difficult the treatment is to detect for a trained gemologist, how often the treated gem might be encountered in the jewelry trade, and how durable the material is to normal handling procedures. Any special care instructions for these treated gems are also provided.

synthetic

A synthetic gem material is one that is made in a laboratory, but which shares virtually all chemical, optical, and physical characteristics of its natural mineral counterpart, though in some cases, namely synthetic turquoise and synthetic opal, additional compounds can be present.

Synthetic gem crystals have been manufactured since the late 1800s, and their production is often marked by a need for them in industrial applications outside of the jewelry industry. The first success was in producing synthetic ruby of faceting quality. Synthetic crystals are used in communications and laser technology, microelectronics, and abrasives. Because synthetics for jewelry applications can be “made to order” [i.e. consistent color and crystal shape] given the right ingredients, time, and the facilities to grow them, they are likely to be much less rare than natural gems of equal size, clarity, and saturation of color. Because of this, and because it is possible to confuse them with gems that are naturally occurring, there are strict guidelines regarding how they are marketed and sold.

In the United States, the Federal Trade Commission requires that any gem material produced in a laboratory be described in a way that leaves no doubt that it was not produced naturally. It is considered to be a deceptive practice if a synthetic gem material’s origin is not clearly disclosed throughout the distribution channel at the time of sale, from the manufacturer to the consumer. There are also a number of industry organizations such as the American Gem Trade Association (AGTA), the International Colored Gemstone Association (ICA), and the World Jewellery Confederation (CIBJO) that have formulated specific guidelines for their members regarding the disclosure of synthetic gems at the time of sale. In the last decade fewer new kinds of man-made gem materials have been marketed. This suggests that the repertoire of synthetic gem materials is close to reaching its limit in terms of the creation of new materials, but it is not limited in production which is still very significant. During the last century, researchers have developed a number of different ways to create these synthetic gem materials in the laboratory. Most of these methods fall into two major categories – melt or solution.

In melt processes, the chemical composition of melt is the same as the composition of the resulting crystal. In solution processes, the solution or melt has a different chemical composition than that of the resulting crystal. Constituents are dissolved in the solution or melt at high temperature, and the crystal forms initially on a seed crystal as the melt temperature is lowered. Some of the main synthetic processes include:

Geuda Heat treatment

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Geuda Heat treatment

Detailed literature survey is presented on gem minerals, corundum family of gems, colour in gem s tones and heat treatments. Physical and chemical investigations on gem minerals are conducted to understand the nature of treatable stones. Treatable stones are characterized by the presence of different types of impurities in the basic corundum structure. Optimum heating rates, cooling rates and soaking periods are established for geuda and ottu stones. Investigations carried out on over one thousand and twenty samples revealed that certain types of geuda stones can be converted into good blue sapphires while other varieties become light blue or dark blue stones. Removal of bluish and brownish tints in red geuda A comparative stones are not completely satisfactory. Study of the Lakmini furnace with the Toda furnace was carried out to ascertain the more economic one.

Burning machine (New)

Traditional system

As a consumer, you will regularly encounter in the marketplace gems that have been treated to change their appearance. A topic that often comes up is whether a particular gemstone is or isn’t treated. In a sense, humans alter all gem materials after they are found in the earth in order to prepare them for use in jewelry. Natural gem crystals are transformed from their rough crystallographic form into the shapes, outlines, and degrees of polish in the gemstones that we appreciate and wear in jewelry. These steps are and have always been the routine procedures used for manufacturing gemstones. Beyond traditional cutting and polishing, however, gems can often be treated in ways meant to alter their color or clarity. In addition to enhancing their appearance, the process may also improve (or in some cases diminish) the gem’s durability. Because these treatments are not always apparent to the unpracticed eye, and are sometimes difficult to distinguish even by experts, it is necessary and legally required for anyone selling a gem (including consumer to consumer trade) to disclose the treatment procedure it may have received.
Non-disclosure of this treatment could cause a person to believe that a particular gemstone was of higher quality naturally and therefore be more valuable than it actually is. An added challenge is that treatments can be permanent, long lasting, or short-lived under normal jewelry use. Treated gems may require special care by their owner. In the United States, the Federal Trade Commission has established a set of consumer guidelines outlining the need for treatment disclosures and special care requirements, and countries around the world either adhere to similar guidelines, or have regulations of their own. Additionally there are several professional organizations such as the AGTA or the ICA or CIBJO that have formulated specific guidelines that their members are required to follow regarding the disclosure of treatments in gem materials. The following glossary includes terms that are often used in the gem treatment nomenclature, and that you may encounter when shopping for gemstones. Finally, treatments for gemstones are constantly being changed and refined, and the detection of these new treated gems is an important part of ongoing gemological research.

After burning Process

Natural gem Stones in Sri lanka

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Natural gem Stones in Sri lanka

Yellow sapphire 2crt

Red Sapphire

Blue Sapphire

Multi color lot

MASTER CUTTING the Ruby 55.37 cts

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Ruby cutting

Brilliant sapphire cut of Ruby.....

Gem cutting

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Cutting The King of the Ocean 150ct Tourmaline

MASTER CUTTING the Exceptional 55.37 cts TSAVORITE

Ruby cutting

What is Gemstone

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what is gem stone???

To be regarded as a gemstone a mineral(or occasionally an organic material) must be beautiful, most importantly in its color.

Five major gem stones

Diamond ......

Diamond is the hardness mineral on earth and this combined with its exceptional lustre and

brilliant fire,has made it the most highly prized of all gems. Pure, colorless diamond is the most popular, But other varieties from yellow and brown to green, blue, pink, red, gray and black-are also found, depending on the impurities present. Because of the uniform arrangement of their constituent carbon atoms, diamond crystal are well formed usually octahedral with rounded edges and slightly convex faces.Their prefect cleavage facilities the early stages of fashioning but they can only be polished by other diamonds.

Star sapphire.....

All gem quality corundum that is not red is called sapphire yet this name is popularly associated with the color blue. Variation in color,due to iron and titanium impurities, spams many shades but most valuable is a clear deep blue. Some stones, called "color change sapphire" exhibit different shades of blue in artificial and natural light.Good quality sapphire is found in Burma,Sri lanka and india.The best indian sapphire is cornflower blue,and found in kashmir,either in pegmatites or as waterworn pebbles in alluvial deposits.

Ruby.....

Ruby-the name given to red,gem quality corundum is one of the best gemstones for jewellery settings. Rubies may be any shade of red,from pinkish to purplish or brownish red,depending on the chromium and iron content of the stone. Frequently twinning of the crystals makes the material liable to fracture,yet ruby is a tough mineral,second only to diamond in hardness.Crystal prisms are hexagonal with tapering or flat ends. As the crystals grow they from new layers, and depending on the geological conditions and minerals present,color variations,called zoning,occur.

What Are The Ruby Treatments?

A treated Ruby is not a bad thing. Less than 1% off all Rubies that are recovered from the ground actually make it to the market without any treatment. These are the most precious and value Rubies available. If they did not treat Ruby gemstones, 99% of the Ruby would never make it to the market. That means the average person may never see a Ruby in their whole life if it was not for treatments.

Untreated Ruby

By far the rarest and most valuable Ruby gemstone. These stones ave been mined out of the ground, cut and polished and presented to the market. No other process apart from cutting and polishing has been performed on these Rubies.

Heat Treated Ruby

This technique has been used for centuries to treat Ruby gemstones. It is used to improve the clarity and colour of Rubies. The Ruby is placed in a crucible and heated to extreme temperatures of around 1800 degrees. The atmosphere around the Ruby can be altered to change the way the Ruby reacts but the basic idea is that the heat will dissolve any rutile inclusions inside the stone which will improve the clarity and improve the red colour. No other additives have been added to the process and the Ruby is as strong and durable as the unheated version.

Fluorite......

Formerly called fluorspar, fluorite has limited use as a gemstone because it is relatively soft and therefore easily scratched. however the wide range of colors(including yellow,blue,pink,purple and green) the frequent incidence of more than one color is a single specimen and zoning or patchy distribution of color, make in an interesting stone.Despite its fragility and prefect octahedral cleavage stone may be faceted and can be polished very brightly. Cabochons of fluorite have been capped with rock crystal to protect them from scratching.

Pyrope(Garnet).......

The blood - red color of pyrope is due to its iron and chromium content.It rarely has inclusions,but when present they are rounded crystals or having irregular outlines. As with garnets pyrope has no cleavage and fracture is to uneven.But when present they arerounded outlines.

Spessartine(Garnet).......

Gem-quality spessartine is uncommon. It is bright orange when pure, but an increase in the iron content makes the stone darker orange to red. Inclusions are lace- or feather-like.

*OCCURRENCE Spessartine occurs in granitic pegmatites and alluvial deposits. It is found in Sri Lanka, Madagascar, Brazil, Sweden, Australia, Burma, and the USA; also Germany and Italy, but crystals there are too small to facet.

• REMARK Spessartine is named after the Spessart district of Bavaria, Germany. It can be confused with hessonite garnet or yellow topaz, but on close examination of inclusions it is distinguishable

Topaz

Topaz is a silicate mineral of aluminium and fluorine with the chemical formula Al₂Si O₄(F, OH)₂. Topaz crystallizes in the orthorhombic system, and its crystals are mostly prismatic terminated by pyramidal and other faces. It is one of the hardest naturally occurring minerals (Mohs hardness of 8) and is the hardest of any silicate mineral. This hardness combined with its usual transparency and variety of colors means that it has acquired wide use in jewellery as a cut gemstone as well as for intaglios and other gemstone carvings.

Ceylon GEM page

Silver

Gold

IMITATION AND ENHANCEMENT

Synthetic Gemstone

HISTORY AND FOLKLORE

GEMS THROUGH THE AGES

POLISHING CARVING AND ENGRAVING

Faceting

NATURAL INCLUSIONS

Optical Properties

What makes color?

CRYSTAL SHAPES

CRYSTAL SYSTEMS

AQUAMARINE

Geuda Heat treatment

Geuda Heat treatment

Natural gem Stones in Sri lanka

MASTER CUTTING the Ruby 55.37 cts

Gem cutting

What is Gemstone

what is gem stone???

Five major gem stones

Diamond ......

What Are The Ruby Treatments?

Untreated Ruby

Heat Treated Ruby

Topaz

Mining & Heat Treatment