A gemstone is the naturally occurring crystalline form of a mineral which is desirable for its beauty, valuable in its rarity, and durable enough to be enjoyed for generations. There are more than 30 popular gem varieties and many more rare collector gemstones. Some varieties also come in a range of colors.
The Gem industry in Sri Lanka (also known as Ceylon, Serendib, etc..) has been in existence for over 2500 years. Some of the rarest of gem stones of exquisite beauty have taken pride of place, in the Crown jewels of Kings and Queens from time of Great Roamn Emperors.
Coloured varieties, star sapphire, alexandrite-like sapphire.
Sri Lanka, Kashmir (India), Burma, Thailand, Australia, Tanzania, Kenya, Montana, Madagascar.
Excellent, except in laminated or fractured stones.
Sapphires may fade if heated
Sapphires can be x-rayed to intensify their colour. Natural sapphires undergo heat and diffusion treatments in Thailand. With the first method, sapphires with latent chemical components for good colour are “ripened” to a desirable colour through heating. In diffusion treatment, sapphires that lack the components for good colour are placed in a bath of colouring oxides that penetrate the outer layers of the stone. Treatment of blue stones is permanent.
According to an ancient Persian legend, the earth rested on a great sapphire whose reflection was seen in the sky. The stone also appears in the Promethean legend. Prometheus was chained to a rock by Zeus for having stolen fire from the gods. After being rescued by Hercules, a link of the chain remained on his finger, and attached to it was a piece of rock. Zeus agreed to grant Prometheus his freedom if he wore the link as a reminder of his sin. Later a ring set with a sapphire replaced the link and stone. Sapphire symbolizes truth, sincerity and constancy. It was believed to protect the wearer against capture by an enemy, and to win the favour of princesses. It also protected against poison. It was said that if a poisonous snake were put in a vessel with a sapphire, the rays from the gem would kill it. The name sapphire originally comes from Sanskrit. It became sappheiros in Greek, meaning blue. Before the value of sapphire was known to them, villages in the Zanzkar mountains of Kashmir (India) used the gem as a flint to start fires.
Faceted and en cabochon, usually mixed cut, beads, carved (poor quality). Synthetic sapphire is used in watches, precision instruments and electronic equipment.
Sapphires that show a star-like light effect are called star sapphires; the most famous star sapphire from
Sri Lanka is displayed in the Museum of Natural History in New York. Star sapphires or star rubies display a star-like marking and this effect, commonly known as asterism, occurs when light falls on the cut stone, cut in the cabochon form, and three rays appear giving a six-point star. However, stones with six rays have also been known to occur.
Lastly, there is milky corundum, a white opaque form of corundum also called geuda, which for many years was regarded as useless and discarded, often ending up lining fish tanks in some gemstone merchant’s house. This happened until dealers in Thailand learned to heat-treat geudas to change the colour of the stone from an unattractive cloudy grey-white to a bright, sparkling blue. They completed the work nature began and ended up with a blue sapphire – of much greater value than a useless pebble. The colour of heat-treated blue sapphires are stable and the chemical composition of the stone is that of a sapphire, although prices are lower than for a similar quality stone with natural colour.
The most famous sources for sapphire are Kashmir and Burma, (now known as Myanmar). Kashmir sapphire, which was discovered in 1881 when a landslide in the Himalayas uncovered beautiful blue pebbles, has a rich velvety colour prized by connoisseurs. Burma sapphires, from the same region that produces fabulous rubies, are also very fine. However, today, these two sources account for a very small quantity of the sapphire on the market.
Most fine sapphire on the market today comes from Sri Lanka, which produces a wide range of beautiful blues from delicate sky blue colours to rich saturated hues. Kanchanaburi in Thailand and Pailin in Cambodia are renowned for deep blue, even colours. Two relatively new mining localities are showing promise: Madagascar, which has produced some exceptionally fine stones in small sizes but has no organized mining yet, and Tanzania, which has long produced sapphire in other colours but is starting to produce blue colours as well from a new deposit in the south.
The most valuable sapphires have a medium intense, vivid blue colour. The best sapphires hold the brightness of their colour under all different types of lighting. Any black, grey, or green overtones mixed in with the blue will reduce a stone’s value. In general, a more pastel blue would be less preferred than a vivid blue but would be priced higher than an overly dark blackish-blue colour. As with all gemstones, sapphires, which are “clean” and have few visible inclusions or tiny flaws are the most valuable.
Sapphires are most often cut in a cushion shape – a rounded rectangle – or an oval shape. You can also find smaller sapphires in round brilliant cuts or a wide variety of fancy shapes, including triangles, squares, emerald cuts, marquises, pear shapes, baguette shapes, cabochon cuts and smooth domes.
Sri Lanka, Burma, Thailand, Africa (Kenya, Madagascar, Tanzania), India.
Excellent, except in laminated or fractured stones.
The Burmese believed that “blazing red” stones could be found in a “bottomless” valley. Natives threw pieces of meat into the valley, hoping that some stones could then be recovered by killing the vultures. In the Royal Collection of England, you can view a gold ring set with a pale but nearly flawless ruby into which a portrait of Louis XII of France is carved.
Faceted or en cabochon, usually mixed cut (brilliant crown, step-cut pavilion), beads, carved (poor quality).
The most important factor in the value of a ruby is colour. The top qualities are as red as you can imagine: a saturated pure spectral hue without any overtones of brown or blue. The word red is derived from the Latin word for ruby, ruber, which is derived from similar words in Persian, Hebrew, and Sanskrit. The intensity of colour of a fine ruby is like a glowing coal, probably the most intensely coloured substance our ancestors ever saw. It is no wonder they ascribed magical powers to these fires that burned perpetually and never extinguished themselves.
Besides colour, other factors that influence the value of a ruby are clarity, cut, and size. Rubies that are perfectly transparent, with no tiny flaws, are more valuable than those with inclusions, which are visible to the eye. Cut can make a big difference in how attractive and lively a ruby appears to the eye. A well-cut stone should reflect backlight evenly across the surface without a dark or washed-out area in the centre that can result from a stone that is too deep or shallow. The shape should also be symmetrical and there should not be any nicks or scratches in the polish. Rubies and other gemstones are sold per carat, a unit of weight equal to one-fifth of a gram. Larger rubies, because they are more rare, will cost more per carat than smaller stones of the same quality.
The Ruby sometimes displays a three-ray, six-point star. These star rubies are cut in a smooth domed cabochon cut to display the effect. The star is most visible when illuminated with a single light source: it moves across the stone as the light moves. This effect, called asterism, is caused by light reflecting off tiny rutile needles, called “silk,” which are oriented along the crystal faces.
The value of star rubies and sapphires are influenced by two factors: the intensity and attractiveness of the body colour and the strength and sharpness of the star.
All six legs should be straight and equally prominent. Star rubies rarely have the combination of a fine translucent or transparent colour and a sharp prominent star. These gems are valuable and expensive.
The most famous source of fine rubies is Burma, which is now called Myanmar. The ruby mines of Myanmar date back to centuries ago: stone age and bronze age mining tools have been found in the mining area of Mogok. Rubies from the legendary mines in Mogok often have a pure red colour, sometimes described as “pigeon’s-blood”, although that term is more fanciful than an actual practical standard in the trade today. Myanmar also produces intense pinkish red rubies, which are vivid and extremely beautiful. Many of the rubies from Burma have a strong fluorescence when exposed to ultraviolet rays like those in sunlight, which layers on extra colour. Burma rubies have a reputation of holding their vivid colour under all lighting conditions.
Sri Lankan stones are often pinkish in hue and many are pastel in tone. Some, however, resemble the vivid pinkish red hues from Burma. Rubies from Kenya and Tanzania surprised the world when they were discovered in the sixties because their colour rivals the world’s best. Unfortunately, most of the ruby production from these countries has many inclusions, tiny flaws that diminish transparency. Rubies from the African mines are rarely transparent enough to facet. However, their fantastic colour is displayed to full advantage when cut in the cabochon style. A few rare clean stones of top quality have been seen.
Occasionally a few fine, top-quality rubies appear on the market from Afghanistan, Pakistan or the Pamir Mountains of the Commonwealth of Independent States. The terrain in these areas has made exploration for gemstones very difficult but someday they may produce significant quantities for the world market.
A very small amount of alexandrite shows a cat’s eye effect (chatoyancy).
Sri Lanka, Tanzania, Soviet Russia, Brazil, Zimbabwe – Rhodesia, Burma.
Alexandrite received its name because it was discovered on the birthday of
Czar Alexander II of Russia in 1830. Red and green are also the colours of the Russian Imperial Guard.
Alexandrite is usually faceted. Chrysoberyl cat’s eyes must be cut en cabochon to display a chatoyant effect.
Sri Lanka is the best known source for star sapphires and star rubies. Star sapphires range in colour from grey to bluish-grey and from medium blue to medium dark blue. The very slightly purplish medium dark blue is the best colour grade for star sapphires. Star rubies range from light pink-red to purple-red through deep purple-red. The intense red star rubies are extremely rare. A good quality star stone should have a high degree of transparency and a well defined star with no weak or missing rays. It should be reasonably clean and in the face-up position, no distracting inclusions or cracks should be seen. There should be no excess weight at the bottom of the stone.
Star sapphires and rubies are hard stones (9 on the Moh?s scale), which can take a high degree of polish and retain the shinefor a long time.
The special optical phenomenon of a well-defined six-ray star is a fascinating sight. The wearable qualities of the star stones make them suitable for men’s rings.
There are generally two varieties of cat’s eye the alexandrite cat?s-eye and the chrysoberyl cat’s-eye, which is very popular in the Far East, particularly in Japan. The ideal colours of the chrysoberyl cat’s-eye are yellowish-brown, which is called the honey colour, and the yellow-green, which is called the apple green colour. A very good cat’s eye, apart from being of ideal colour, should have a high degree of transparency and a well-defined unbroken ray. It should be free from any distracting inclusions visible to the unaided eye. The chrysoberyl cat’s-eye is one of the most beautiful gemstones because of the chatoyancy or the eye effect.
A translucent variety of chrysoberyl (beryllium aluminum oxide) which exhibits a silvery white line across the stone. This moves as the stone, the light source or the observer moves and may appear to open and close like an eye.
The finest quality has a sharp eye that appears to open and close as the stone is rotated, and exhibits a strong “milk and honey” effect (stone on one side of the eye appears lighter than the other). These colours switch as the stone or [light source is moved. The most highly prized body colours are greenish-yellow and brownish-yellow (honey colour).
Rare specimens also exhibit change of colour. Sources Sri Lanka, Brazil.
Chatoyancy caused by the reflection of light off minute, parallel, needle-like rutile crystals or hollow tubes.
When a gem specimen exhibits both chatoyancy and change of colour, one or both phenomena will suffer. It is more common to find a good eye with poor change of colour. The conditions necessary for one phenomenon conflict with those needed for the other. The term cat’s eye when used alone refers to chrysoberyl. Other minerals exhibiting chatoyancy must be qualified, e.g. tourmaline cat’s eye.
Cat’s eye has been regarded as a preserver of good fortune. The natives of Sri Lanka still consider it a charm against evil spirits. British royalty often use it as an engagement stone.
Must be cut in a cabochon to produce cat’s eye effect. This should be cut so that the long portion of the cabochon is 90 degrees to the direction of the needles.
Gem varieties of quartz include: citrine, amethyst, rock crystal, rose quartz, and smokey quartz. There are also varieties of Quartz cat’s eye.
Colours: citrine (yellow); amethyst (purple); rock crystal (colourless); rose quartz (pink); and smokey quartz (purplish-brown).
Sri Lanka, Brazil, Uruguay, Russia, Mexico, Zimbabwe – Rhodesia, Zambia, Arizona.
The word amethyst comes from the Greek amethustos meaning “not drunk”. Therefore, it has been considered a charm against intoxication. A legend accounts for the origin of the stone. Supposedly, Bacchus, the god of wine and conviviality, grew angry at a slight and swore revenge. He decreed that the first mortal to come across his path was to be eaten by tigers. Amethyst, a beautiful maiden on her way to worship at the shrine of Diana, happened to be the victim. Diana, the huntress, changed Amethyst into colourless quartz to protect her from the tigers. When Bacchus witnessed the miracle, he repented and poured wine over the stone, staining it purple. The wine failed to cover the entire stone evenly, and the feet and part of the legs remained clear crystal.
So, in keeping with the legend, amethyst crystals are usually uneven in colour with a colourless base. Cuts & Uses Must be cut in a cabochon to produce cat’s eye effect.
Madeira (deep, bright reddish-brown) and Palmyra (medium yellowish-brown) are terms used in the trade.
Brazil, Madagascar, Russia, Sri Lanka.
Poor quality amethyst is often heat-treated to achieve a desirable citrine colour.
Usually fashioned into ring and pendant stones. The per carat value of cut citrine usually decreases beyond the size of an average ring stone.
May occasionally exhibit a cat’s eye effect (chatoyancy).
Sri Lanka, Brazil, Madagascar (only historically), Tanzania, Russia, Kenya, Afghanistan, Nigeria.
Almost all aquamarine is heat-treated to enhance its blue colour. Irradiation with neutron, gamma rays or with x-rays. Colour change is permanent and is an accepted practice. A morganite (pink beryl) turns deep purple blue (Maxixe type) upon ultraviolet irradiation, though the colour is not stable.
The word aquamarine comes from the Latin for sea water. In 1910 a 243 lb. crystal was found in Brazil. The outside was greenish and the inside was blue. It sold for $25,000 and was cut into many high quality gems. The American Museum of Natural History has a 13 lb. uncut piece of the green outside portion.
The step-cut is the most popular because it accentuates the colour. As it is often found in large, flawless, even-colored crystals, it is frequently used in pendants and rings. Given a piece of rough with a certain colour intensity, the larger stones cut from it will exhibit deeper colour.
Other Information Aquamarine is the blue, or perhaps more correctly, blue-green or aqua variety of the mineral beryl. Other gemstone colour varieties that belong to beryl include emerald, morganite, and heliodor. Other colours of beryl are simply referred to by their colour, such as red beryl. Most gem aquamarines have been heat treated to produce the popular blue-green varieties from less desirable yellow or pale stones.
Rhodolite- violet to purplish-red;
Almandite – red, brownish-red, violetish-red or purple;Pyrope red;
Grossularite – green, yellow, brown, white, colourless, light violet, red, orangey-red; Varieties: hessonite (orange to brown), transparent, green, grossularite (tsavorite);Some show a colour change from a mauve-brown to orange-red.
Andradite – green, yellow, black. Green called demantoid (high lustre and dispersion);
Spessartite – yellow to yellow-brown, dark orangey-brown, reddish-orange, orange;
Uvarovite – emerald green, found only in tiny sizes, usually opaque.
Rhodolite – Sri Lanka, North Carolina, Tanzania, Kenya, South Africa, Brazil.
Almandite – Sri Lanka, India, Brazil, star from Idaho – USA.
Pyrope – Czechoslovakia, South Africa, Zimbabwe – Rhodesia, Brazil, Arizona.
Grossularite – Sri Lanka, Brazil, Tanzania, Kenya, South Africa, Canada.
Andradite – demantoid: Russia, Italy; translucent yellowish or greenish-brown, Arizona.
Spessartite – Sri Lanka, Burma, Brazil, Madagascar, Tanzania, Kenya.
Uvarovite – Russia, Finland (hardly mined at all).
Fair to good
Since earliest times garnets have been carried as amulets against accidents in travel. Asiatic peoples and even our Southwest Indians used them as bullets, believing that their rich, glowing colour might cause more deadly wounds. The Persians have given the garnet a favoured place as a royal stone, allowing it to bear their sovereign’s image. Red garnet was once used to relieve fever, yellow garnet to cure jaundice. If the powder failed, the apothecary was accused of using a substitute.
Usually faceted. Sometimes carved into intaglios.
Bi-coloured, watermelon, cat’s eye, alexandrite-like (rare) .
Sri Lanka, Brazil, USA (California, Maine), Madagascar, Tanzania, Kenya, Russia, Afghanistan, Pakistan (prime new source).
Dutch children played with tourmaline because of its ability to attract light objects. The stones were called “aschentrekkers” (ash drawers).
Any cut may be used. Some are carved, some fashioned into beads. Cat’s eye are always cut en cabochon. Sometimes carved to make use of more than one colour.
Star material is very rare.
Sri Lanka, Burma, Minor-Anatolia, Afghanistan, Brazil, Thailand, Australia. Toughness Good
Two of the stones among the Crown Jewels of England are spinels, although they were once thought to be rubies. They are the Black Prince’s Ruby and the Timur Ruby. The 361 carat Timur Ruby is the world’s most famous spinel. Spinel was recognized as a separate species as early as 1587 in Burma.
Coloured varieties, Imperial (reddish-orange), chatoyant material (very rare).
Prime source is Brazil. Sri Lanka (blue), Mexico (mostly poor quality, brownish-yellow), Russia, South Africa (blue), Utah, Afghanistan.
Poor, extremely easy basal cleavage – treat with care.
The stone began to be used in Marco Polo’s time (13th century). Topaz mounted in gold and hung around the neck was believed to dispel enchantment. When the powdered stone was put in wine, it was considered a cure for asthma, insomnia, burns and haemorrhages. Topaz was supposed to become obscure in contact with poison and to quench the heat of boiling water. All these powers were believed to be increased or decreased with the changes of the moon.
Usually faceted, often mixed cut due to long prismatic shape of crystal; some stones cut as longish oval or pendeloque stones. The moderately rich colored stones are emerald cut.
Some may exhibit cat’s eye effect.
Sri Lanka, Switzerland, Burma, United States, Madagascar, Tanzania.
Phenomena Adularescence- a glowing effect, the finest of which is bluish. Finest quality moonstone is semi-transparent; poorest is translucent. Occasionally a sharp cat’s eye may be present.
Considered a love charm, moonstone has been attributed the power to arouse tender passions and foretell the future. Therapeutic qualities include protection from lunacy, appeaser of anger and relief from fever.
Usually en cabochon, sometimes carved into cameos. Generally used as an inexpensive stone for rings, pendants, etc.
High, medium and low property.
Sri Lanka, Burma, Cambodia, Thailand.
Precautions Avoid heat. Boiling and steaming not recommended.
The terms hyacinth or jacinth were often applied to the reddish-brown zircon. During the Middle Ages, hyacinth was claimed to have the power of inducing sleep, of promoting riches, honour and wisdom and of driving away plagues and evil spirits. The pale yellow to colourless stones from Ceylon (Sri Lanka) were called jargoons.
The round brilliant cut is most successful, standard 57-facets with no culet.[/column]
Peridot top grades: medium to dark, slightly yellowish-green. Chrysolite ? greenish-yellow, light to dark yellowish-green to brownish-green to almost brown.
Sri Lanka, Island of Zeberget (Egypt), Burma, USA, Mexico.
Fair to good
The ancients called it the “gem of the sun.” They attributed to it the power to dispel enchantment and evil spirits due to its association with the sun (which drives away darkness). In order to be worn as a talisman, it had to be set in gold. The Red Sea island of Zeberget, off the southern tip of Egypt, was worked for this stone as early as 1500 B.C. At that time, the island was known as “The Island of Serpents,” because it was infested with poisonous snakes. Later, the reigning Egyptian king had the snakes destroyed to facilitate prospecting for peridot. Prospecting was done at night because the gem could not be seen in sunlight. The workers would mark the spots and return the next day to dig them out.
Usually faceted. Step-cut is best; oval, round and pendeloque cuts are common. Very suitable for brooches, pendants, earrings, but not for rings or bracelets because it abrades easily.