Technicals

Gem Technicals

about
01

DIAMONDS

All our diamonds are natural-natural.
All diamonds over 1 carat are GIA lab certified.
02

RUBIES

Assume that all rubies are heated unless delineated to the contrary. Heated may, in turn, mean that the item is (lightly) oiled and (micro-) fracture-filled, with (minimal) residue possible. Note that we are prime dealers in top-lab-certified Vivid Red Natural Unheated rubies. If Unheated, typically we will furnish Reports from three separate top labs – owing to the extra-high ‘ticket price’ of top-quality Unheated rubies. Note that the current industry ‘standard of excellence’ is (rare) Vivid Red H(a) - with Vivid Red Unheated being even more rarefied.
03

EMERALDS

Assume that all emeralds are oiled or otherwise filled unless delineated to the contrary.
Note that beautiful untreated emeralds are close to non-existent.
Note that we are prime dealers in ‘top drawer’ Gubelin lab-certified ‘minor’ treatment emeralds, the Fifth Avenue technical ‘standard of excellence’.
04

SAPPHIRES

Assume that all sapphires are heated unless delineated to the contrary. Heated may, in turn, mean that the item is (lightly) oiled and (micro-) fracture-filled, with (minimal) residue possible.
Note that we are prime dealers in top-lab-certified Natural Unheated sapphires.
05

PEARLS

99.9% of industry pearls are cultivated/cultured pearls.
All pearls may be subject to some treatment in Asia/Australia.
01

DIAMONDS

Diamond is the best known gem. Its history is so long and complex that the beginning is lost in antiquity.

India was a source of many of the world's most famous diamonds. Diamonds were traded in India as early as four centuries before the birth of Christ,
many gems reaching Ceylon (now Sri Lanka) and the Middle East. Other stones found their way into the Roman Empire, where their supposed magical powers
enhanced their value. Arabian and Persian merchants brought diamonds to China, where they served as jade-cutting and pearl-drilling tools in the first few centuries A.D. Diamond tools were highly regarded in China and were considered gifts worthy of royalty.

Indian superstitions about diamond eventually spread throughout the world. The Buddhists believed that a person's soul had to be purified before
joining the "universal soul," or karma. The steps in this process involved incarnations as animals, plants, and even minerals. This fostered the belief that minerals and gems have life, a notion that persisted for centuries. The Greek philosopher Plato believed in life among gems and rated diamond as the noblest. Such ideas were held well into the Renaissance. Jerome Cardin who, in the 16th Century, first designated stones as "precious," believed that minerals and gems were "born" of the fluids in rock cavities.

Diamond, with its remarkable properties of hardness, dispersion, and brilliancy, was also considered a strong medicine. The powder of white, flawless diamonds would, if swallowed, impart health, energy, and long life.Flawed stones, however, might have the opposite effect! Diamond powder was for centuries considered to be a deadly poison, and the deaths of many prominent rulers and politicians were attributed to this agent. Diamond was supposed to have many other mystical powers. If held in the mouth, a diamond would cause the teeth to fall out. It repelled phantoms and demons, and prevented nightmares. Diamonds could ward off magic and protect the wearer in battle by giving him courage, virtue, and invincibility.

Fabulous diamonds symbolized wealth and power. They were regarded as emblems of rank and status. In times of political upheaval and uncertainty, diamonds also represented easily portable wealth. The history of diamond constantly links together attributes of power, magic, and great value. The incredible beliefs about this gem have been embellished through the centuries. But they are undoubtedly derived from the truly remarkable properties that diamond does display.

 

Forms and Colors

Diamond crystals occur in a variety of shapes and forms. The most common shape resembles two four-sided pyramids arranged base-to-base and is known as an octahedron, an eight-sided form. The directions of easy cleavage in diamond are parallel to the octahedral faces. Other forms seen on diamond crystals include the cube and dodecahedron, the latter an interesting 12-sided form. Some rough diamond crystals are combinations of several of these forms. Also frequently present on diamond crystal surfaces are triangular pits called trigons, believed to have formed during crystal growth.

Diamonds occur in a wide range of colors. The most familiar are basically white or colorless, usually with a tinge of yellow or gray. Richly colored stones, called fancies, are rare and highly prized. Fancy colors include golden-yellow, blue, green, pink, and amber.

Fine yellow diamonds with so-called “canary” color make notable gems. Two of the best-known yellow diamonds are the Florentine (137.5 carats) and the Tiffany (128.5 carats).

Diamond is pure carbon, the element that is also the foundation of life. Carbon has interesting chemical properties that enable it to form a truly vast number of compounds with many other elements. Some of these are biologically active. Another form of pure carbon is the mineral graphite. Graphite is so easily powdered that it is used as the
“lead” in pencils (mixed with clay for this application), and so greasy that it is widely used as a lubricant. Yet diamond is the hardest known substance, and will easily scratch any other material.

updated: May 24, 2016     David Birnbaum   Rare 1
02

RUBIES

Few gems have the mysterious depth of color, the glittering history, and the aristocratic dignity of corundum gems. Pure corundum is colorless. The red variety is termed ruby.

Corundum is aluminum oxide. It occurs throughout the world in various kinds of rocks, sometimes in large crystals. But crystals of rich color that have transparent areas large enough to yield gems are very scarce, and fine rubies and sapphires are therefore highly prized and very costly.

To the Hindus ruby, the Lord of Gems, seemed to burn with a kind of inextinguishable fire, capable of boiling water. According to the Greeks, it could melt wax on which it was impressed. The ruby was believed to exert powerful forces. It could guard a home or orchards against storms. It could preserve mental and bodily health. It could control passion and amorous thoughts, reconcile disputes, warm corpses of mummies, and, if taken internally, even cure hemorrhages and other illnesses. The Burmese believe that if a ruby was embedded in the flesh of its owner by inflicting an intentional wound, its presence would confer invulnerability.

A gem can be called a ruby only if it is corundum of a red or purple- red hue and medium to dark in shade. A pink or light- red corundum would more properly be called a pink sapphire. The finest rubies known come from Burma, although Burma also produces stones of lesser quality. The finest red- colored Burmese gems have been called “pigeon’s blood,” and the most important producing area in Burma centers around the city of Mogok. Rubies have been mined here for more than 700 years. The geology is distinguished by the presence of very old metamorphic rocks and large bodies of marble, both of which are cut by pegmatite dykes. This has given rise to a huge variety of minerals, and no other locality in the world produces as great a wealth of gem minerals. Most rubies on the market today come from other localities, however are not as fine as Burmese gems.

Corundum typically forms barrel- shaped hexagonal (six- sided) crystals. Since these crystals usually grow at high temperatures they frequently trap and incorporate crystals of other materials in the growth environment. One of the most common of these is mineral rutile, which forms needle- like or fibrous crystals. These fibers align themselves within the host corundum in accordance with the six- fold symmetry of the host. The resulting material displays a diffuse “sheen” due to light reflection off the rutile fibers. If a cabochon is cut from such a corundum crystal the reflected light is focused and concentrated along the top of the stone to form “eyes.” There are three sets of fibers, which intersect to form a six- rayed “star.” Star rubies and sapphires are rare gems, but they can be large and spectacular. One of the world’s finest star rubies is the famous 138- carat Rosser Reeves star ruby, on display at the Smithsonian Institution in Washington, D.C.

A large, clean and fine red ruby is, next to a fancy colored diamond, the most valuable of all gemstones. Burmese rubies have achieved auction prices exceeding $100,000 per carat.

The red color of ruby is due to chromium. The gem trade leans toward acknowledging that a light red stone may be called a ruby. This debate heated up when the very pinkish Vietnamese rubies entered the marketplace in 1991- 92.

The high price of rubies warrants caution in buying. At least five different methods are used to manufacture ruby, and it may require a well- equipped gemological lab and experienced gemologists to authenticate a stone. Star corundums are also made by gemologists to authenticate a stone. Star corundums are also made by various manufacturers, and some look deceptively like natural gems.

Rubies make fine ringtones. They are brilliant gems and when properly cut catch and return considerable light to the viewer. Faceted corundum gems weighing more than ½ carat may be expensive. However, the small stones generally used in cluster rings that weigh only five or ten points are not expensive. This is an important buying consideration, because a ring, for example, with ½ carat of small single ½ carat stone.

updated: May 24, 2016     David Birnbaum   Rare 1
03

EMERALDS

Emerald was dedicated by the Greeks to the goddess Aphrodite (- Roman goddess Venus). Cleopatra’s emerald mines were worked as early as 2000 B.C. and provided many stones for the craftsmen of the ancient world. For centuries emerald has been a wellspring of mystery and superstition. It is the symbol of immorality and of faith. It was once believed that gazing at an emerald was beneficial to the eyes. The subtle change of color sometimes present in the gem was thought to symbolize the inconsistency of lovers. Emeralds may not have magical powers, but it does have a mystique. It is one of the rarest and most valuable of all gemstones.

Cut emeralds of top quality weighing more than several carats are extremely rare and costly. A large deep stone with minor blue or yellow secondary coloration and relatively free of emerald’s customary wispy inclusions may cost tens of thousands of dollars per carat.

The best known locality for emerald is Columbia, where mines have produced for centuries. Emeralds were mined in Russia from 1803, when a peasant noted some green stones at the foot of a tree uprooted by a storm. Russian emeralds are greatly prized and are deep green, but not of the best hue, and crystal have yielded only small stones that are relatively free of inclusions and flaws. Brazilian emeralds have been avidly sought since the middle of the 16th Century. The lure of “green wealth” helped to open up the interior of this vast country. Some of this emerald is of fine quality, almost on par with Columbian material. Though much exploration has been done, no deposits of emerald comparable to those of Columbia have been found elsewhere in South America.

The Columbian emerald mines at Muzo and Chivor produced the finest emeralds ever known. Pizarro, after his conquest of Peru, sent back to Spain numerous emeralds of fantastic size and quality. It is said that the ancient Peruvians worshipped, among other things, a fine emerald the size of an ostrich egg. Today the Colombian government operates the emerald mines. Since 1934 all persons involved in the cutting and selling of Columbian emeralds have had to register with the government, and exports are strictly controlled.

Emeralds are known from Australia, South Africa, Rhodesia, Zambia, Norway, and India, but these are far less important than the Columbian deposits. Fine emeralds have been recovered in North Carolina, and excellent quality stones in the 10- 20 carat range have been cut from this material. Emeralds have characteristic inclusions by which they can be identified and distinguished from the synthetic, or man- made emeralds produced in recent years.

The most popular cutting style for most beryls is a step-cut rectangle with the corners truncated; this cutting style produces a characteristic shape known as the emerald cut. Other popular beryl cuts include the cushion cut, a simple rectangle; the octagon, which is basically a square emerald cut; and the round brilliant.

The beryls are all fairly tough gems, with the exception of emerald. Because of its typically present inclusions and flaws, emerald is a fragile gem and requires care in mounting and wear. The hardness of beryl is 7.5-8 on the Mohs scale, which is ample for ringstones.

updated: May 24, 2016     David Birnbaum   Rare 1
04

SAPPHIRES

Few gems have the mysterious depth of color, the glittering history, and the aristocratic dignity of corundum gems. Pure corundum is colorless. Blue corundum is called sapphire. All other colors are simply termed sapphire with a color- designating prefix, such as green sapphire, pink sapphire, and so on.

Corundum is aluminum oxide. It occurs throughout the world in various kinds of rocks, sometimes in large crystals. But crystals of rich color that have transparent areas large enough to yield gems are very scarce, and fine rubies and sapphires are therefore highly prized and very costly.

Sapphires were believed to attract divine favor to their owners. A gem could preserve its wearer from envy, protect against captivity, and serve as a key to understanding the sayings of oracles. Sapphire is the gem of autumn, and of the soul. The bishop of Rennes in the 12th Century praised the virtues of the sapphire and started the long history of the use of this gem in church regalia.

Sri Lanka (Ceylon) also produces ruby and sapphire, especially in the area around Ratnapura, which in Singhalese means “city of gems.” Mining methods here are similar to those in Burma, and the occurrence of gemstones is also in lenses or pockets of gravel buried at some depth. Ceylon ruby tends to be paler than material from Burma. But Ceylon sapphires are among the world’s finest, and occur in all shades of blue (usually with a slight tinge of violet), as well as yellow, green, blue- green, brown, pink, and colorless. A very rare pinkish- orange color, prized since antiquity, is called “paparadschah” which means “lotus blossom.”

Thai sapphires are commercially important and typically are dark blue. The main localities are Bo Ploi, Chanthaburi and Kachinaburi. Sapphires from Cambodia, especially from Pailin, have been commercially important. Some of the world’s finest and most famous sapphires come from India in Kashmir, high in the Himalayas.

Australia is important for its enormous production of extremely dark blue and blue- green sapphire from Anakie, Queensland. These gems are grayish/ blackish and tend to be very dark when faceted. In the United States gem corundum is known from North Carolina (no commercial significance except to rockhounds) and especially from Montana. Fine sapphires occur here in three main occurrences: as rounded, pale gravels in the Missouri River; as alluvial gravels in the Rock Creek area; and as fine (but small) blue and multi- colored crystals at Yogo Gulch in both alluvium and an enormous igneous dike. Yogo material is “cornflower blue” but cut gems are usually tiny and mining is expensive. Heat treatment of Rock Creek sapphire yields the finest corundum colors in North America. Missouri River material can also be treated but the yield of fine colors is low.

The world’s largest fine blue star sapphire, the 563- carat Star of India, is displayed at the American Museum of Natural History in New York City, the gem Star corundums are seldom transparent, because the star is produced by reflections of fibers of rutile “silk” included within the sapphire; the silk needed to produce the star also defeats the transparency of the host. Value in star corundum is a function of the body color of the stone, the perfection of the star (all legs present and straight), it’s centering within the cut gem, and the star’s intensity. In hardness corundum is second only to diamond, and rates 9 on the Mohs scale. Cut gems are both hard and durable, and wear extremely well.

Star sapphires are rare gems, but they can be large and spectacular. The world’s largest fine blue star sapphire, the 563- carat Star of India, is displayed at the American Museum of Natural History in New York City, the gem Star corundums are seldom transparent, because the star is produced by reflections of fibers of rutile “silk” included within the sapphire; the silk needed to produce the star also defeats the transparency of the host. Value in star corundum is a function of the body color of the stone, the perfection of the star (all legs present and straight), it’s centering within the cut gem, and the star’s intensity. In hardness corundum is second only to diamond, and rates 9 on the Mohs scale. Cut gems are both hard and durable, and wear extremely well.

updated: May 24, 2016     David Birnbaum   Rare 1
05

PEARLS

Pearls are one of the most classic and eternal pieces of jewelry a woman can own. David Birnbaum / Rare 1 only sources the most luxurious and valuable strands of pearls, guaranteed to add luster any woman’s collection.

To ancient man the natural forces around him inspired reverence and awe. The sun and moon were deities with formidable powers over the lives and destinies of men. The discovery of a glimmering, lustrous object from the sea that seemed to embody the glow of the full moon was undoubtedly the inspiration for a new cult. It is believed that peals were known and esteemed 3,500 years before Christ. To the ancients the sea was the source of all life. And in the lands around the Mediterranean, a shell cult developed that brought such status to the pearl that is remained a Queen of Gems.

The pearl is actually the response of a mollusk to the presence of an irritating impurity in its body. Saltwater pearls are found in non-edible oysters, and freshwater pearls in mussels (clams). The principal genus of oyster associated with saltwater pearls in Pinctada, and Unio is the primary freshwater pearl-producing clam genus. Many other types of mollusks produce concretions in the bodies, but few display the iridescence associated with gem pearls.

Within the two hinged shells of the Pinctada mollusks are various tissue layers. Mother-of-pearl is the layer to which the body parts are attached, lining the inside of the shell. If an irritating particle, such as a grain of sand, gets inside the shell, the mollusk’s tissues will start to deposit a protective layer of nacre (mother-of-pearl) around it. This accretion may become a pearl. If the particle is enclosed completely by soft tissue, the pearl may be round and well formed. If the irritating particle becomes attached to the shell of the mollusk, a hemispherical-shaped blister pearl will result.

A pearl is built up in layers concentrically arranged around the irritant. The layers may consist of a mineral produced by the mollusk; but unless the outer layers consist of nacre, the pearl will not display the lustrous iridescence called orient that makes pearls so highly prized and beautiful. Edible oysters cannot manufacture the semi-transparent layers of nacre that are characteristic of gem pearls.

Below the orient, sometimes called overtone, is the body color or background color of the pearl. Overtone is seen in reflected light coming from the surface of the pearl, and its colors include purple, green, yellow, pink, and orange. Body color is subdivided into three basic colors: white, black, and “colored,” including red, yellow, purple, violet, blue, and green. Black pearls include grays as well, plus bronze, dark blue, blue-green, and green pearls with metallic lusters. White pearls include cream-colored, light rose, and cream rose (both with pink overtones), and so-called “fancy” pearls which always have three colors: cream, rose, and a blue or green overtone.

Saltwater mollusks are the most important producers of pearls today, and by far the majority of the world natural pearl production is from the Persian Gulf, between Saudi Arabia and Iran. Only about one mollusk in 40 contains a pearl, and the total number of mollusks recovered tends to be small. From the Gulf the pearls travel to Bombay, where they are cleaned by immersion in hydrogen peroxide and by drying in the sun. After sorting and drilling, the finer grades are sold to Western dealers, and most of these pearls eventually appear in Paris and then the United States. Paris is a major distribution point for pearls. Bombay is essentially a brokerage center.

Fine pearls also come from Sri Lanka, Australia, Japan, Mexico, Panama, Venezuela, and Tahiti. Freshwater pearls are found in the Mississippi River and its tributaries, as well as Scotland and China.

updated: May 24, 2016     David Birnbaum   Rare 1

 

Select Excerpts from Gems and Jewelry, Second Edition, by Joel E. Aren


 

 

David Birnbaum Rare 1 rare jewels is the flagship firm of the renowned 100+ year Birnbaum gem group - transplanted from Europe in the 1930s. Global gem cutters and dealers, the David Birnbaum Private Jewelers optimizes its sourcing and value-added for its illustrious clientele. The firm specializes in the very rarest diamonds, rubies , emeralds and sapphires.  Natural Unheated Burma and Mozambique  Vivid Red  pigeons blood  rubies,  Gubelin-certified Colombian emeralds and  Natural Unheated rare  kashmir,  Burma, Ceylon sapphires. All are part of the extraordinary offerings at David Birnnbaum. Rare and exotic Fancy Color Pink and Blue diamonds are in the David Birnbaum Rare 1 mix.

See also David Birnbaum D Color and Fancy Vivid Yellow diamonds, diamond necklaces, bracelets.

 

David Birnbaum / Rare 1: Natural Unheated Vivid Red Pigeon's Blood Burma & Mozambique Rubies