Coral is another gem material of organic origin; unlike amber, however, which seems to have lost its popularity, it is more in demand that ever. It is the branchlike, calcareous framework of the coral polyp and is formed by the accretion of colonies of these tiny marine animals. The calcium carbonate is in the form of calcite, and the structure is radial from the center of each branch. The calcareous skeleton of a coral colony is firmly attached by a circular-shaped "foot" to any suitable natural or foreign object on the ocean floor. The nature of the cementing process is such that the disc like foot provides a firm foundation for the entire structure. It is interesting to note that a coral colony, unlike a plant, always grows in a direction perpendicular to the surface to which it is attached; if the initial attachment were on the underside of a rock, for example, the direction of growth would be downward.
There are three varieties of coral, but only one of these, the so called precious coral (Corallium Rubrum or Corallium Nobile), is of great significance. It is usually found in light to dark tones of red to orangey red, but sometimes it appears more nearly orange, flesh colored or white. The color is caused by a small amount (approximately 1%) of organic matter, plus some iron oxide. Another kind of coral, a black variety known technically as Corallium Nigrum, is composed almost entirely of conchiolin. Sometimes call "king's coral". It is used almost exclusively in the orient. A third type, blue coral, which was once found in Africa, is now almost unknown.
The superstitions associated with coral are many and varied. Not only was it important to ancient peoples from the standpoint of beauty, but it was used extensively for medicinal purposes. Ground to a fine powder and mixed with water or wine, it was said to cure a wide assortment of human ills. Moreover, it was thought to possess the power to ward off evil, impart wisdom, staunch the flow of blood and drive off fever.
Among the Romans, branches of coral were hung around children's necks to preserve then from danger. A belief in the potency of coral as a charm continued to be entertained throughout medieval times, and even in this century in Italy it has been worn as a preservative from the "evil's eye" and by women as a cure for sterility. Although Pliny points with scorn to most of the exaggeration of the magicians of his day regarding the charms of gem materials, he relates their claims that coral quiets the waves of the sea and makes it calm. Further, he tells how they claim that it preserved the wearer from lightning and terrible tornadoes.
During the height of the Roman civilization, it was an accepted face that a dog's collar set with coral and flint acted as a positive remedy for hydrophobia. Still another belief concerned the preparation and use of a "tincture of coral". After a lengthy and tedious process of heating a branch of coral in melted wax and steeping the resultant product in alcohol, a red liquid was eventually produced. Not only was it said to be an excellent tonic, but, by causing perspiration and diuretic action, it was supposed to have had the power to drive "bad humors" from the body.
The Romans also used coral extensively for fashioning articles of personal adornment, as shown by the brooch and earring set in the accompanying photograph.
Among the more widespread beliefs of early centuries was the theory that red coral changed its hue in conformance with the condition of the wearer's health. According to the writings of Johann Wittick, a German physician of the sixteenth century, the validity of this concept was examplified by the death of a patient whose red-coral necklace turned white with the onset of sickness, then a dirty yellow, and finally, with the coming of death, became covered with black spots.
Popular in eighteenth-century France was a necklace known as a "pater de sang" (blood rosary), which was supposed to check hemorrhages. In a volume treating of superstitions of the period, however, the anonymous author questioned the practicability of the rosary. Assuming that the beneficial effect could only be produced by the thickening the blood, he reasoned that the detriments might very well outweigh the advantages: if the rosary possessed the power at one time, it must possess it constantly, therefore rendering the overall action very dangerous.
In order to retain its remarkable powers as an amulet, early-day superstition dictated that coral must not be carved or otherwise be worked by man: furthermore, it had to be worn in a conspicuous place. Once broken, the magic powers no longer existed.
In ancient Persia, odor played an important part in distinguishing imitation from genuine coral: not without the smell of the sea could it be genuine. The Persians also believed that the precious red coral did not acquire its characteristic color unitl it had been removed from the sea. Among the Chinese and Hindus, coral was held in high esteem, since it was used to ornament the images of their gods. Together with turquoise and amber, coral ranks as one of the most popular gemstones with the people of Tibet. Aside from its esthetic value, it has a deep religious significance, since red is symbolical of one of the incarnations of Buddha. During a visit to Tibet in the thirteenth century, Marco Polo, the Italian explorer, noted the pre dominant use of coral for personal adornment, as well as for ornamenting the idols in their temples.
In certain parts of Africa, strings of coral once possessed a very sacred quality and were regarded as the most priceless gift a ruler could bestow. So greater was the importance of such a royal gift that, should it be lost or stolen, all involved in the incident suffered the penalty of death.
About the beginning of the Christian era, an extensive trade was carried on in coral between the Mediterranean cities and India, where it was highly esteemed as a substance endowed with mysterious sacred properties. Pliny tells us that previous to the Indian demand, the Gauls were in the habit of using it for the ornamentation of their helmets and weapons of war; in his day, however, so great was the Eastern demand that it was very rarely seen, even in the regions that produced it.
An interesting but little known fact concerns the use of coral in articles of jewelry fashioned by the Indian tribes of the southwestern United States. Prior to the coming of Coronado and Cortezt the Pueblo Indians, of New Mexico and Arizona, made extensive use of variously colored fragments of the spiny oyster shell from the Gulf of Mexico. Red was the most highly prized color, and eventually, through inter-tribal trading practices, it also became popular with the Zuni and Hopi peoples. Sometime after 1540, the Spaniards, deciding to take advantage of the natives, love for the red shell, began importing coral and selling it as a superior substitute. Historical records indicate that it was readily accepted and soon became quite valuable, often selling for as high as the equivalent of $100 a pound. Just when this trade first began has not been definitely established, but the oldest available reference bears the date 1822. The center of the activity seems to have been Santa Fe, New Mexico.
Coral is a product of warm, seas, and is found throughout the world in tropical and subtropical waters. Traditionally, the most important source for fine material is the Mediterranean Sea. In areas along the coasts of Tunis, Algeria, Morocco, Sardinia and large parts of Italy are found the most desirable qualities. It is also found off the shores of Corsica, Catalonia and Provence. Other sources include the costal waters of Ireland and Japan. Although it has been found at depths up to 1000 feet, it usually grows in shallow water; i.e., from ten to 50 feet in depth. The color seems to lighten with depth in all of the shallow water species of the Atlantic and the Orient in general, but deep water specimens from the Japanese coast seem to be deeper in color.
Coral has a dull luster in the rough and is almost vitreous when polished. It is sufficiently tough to be worked easily with a knife or file or turned on a lathe, bur it is not hard enough (3 to 4) to take and maintain a high polish. The fracture is splintery and no cleavage is present. The S.G. of pink and white coral is 2.60 to 2.70 and that of the black variety is about 1.32 to 1.495. The R.I. is usually approximately 1.65, because of the presence of its chief constituent, calcite, which has a range of 1.468 to 1.658 and which is optically negative, so that the high reading is the one usually visible. Black coral generally has an R.I. of about 1.56. Since coral is a crystalline aggregate, the reaction in the polariscope of stones that are sufficiently translucent to transmit light is that of an aggregate. Of course, it shows neither pleochroism nor dispersion. Coral blackens in the flame of the jewelers torch or the blowpipe and is attacked by acids.
Coral is seldom confused with other gem materials, since its characteristic structure (described as minutely striped or streaked lengthwise along the branches) and shape make it readily distinguishable.
This appearance is entirely different from that of conch pearl, which may have a somewhat similar color. Conch pearl, however, exhibits a sheen in certain directions and shows a pattern under low magnification that has been likened aptly to flames. White heads cut from the shell of the conch to imitate white coral are identifiable by the parallel growth structure of the shell and its tendency to show a pinkish color zoning; these enjoyed considerable popularity as summer jewelry in the mid-1950's. Other distinguishing features of coral are small, shallow, circular depressions that indicate the growth site of the individual polyps. Minute pits, caused by certain boring-type marine organisms, may also be present. These structural peculiarities, as well as those mentioned above, are illustrated in the accompanying sketches. The circular drawing approximates the streaked appearance as it would appear under high magnification.
The, principal substitutes for coral are celluloid, wood and sealing wax, none of which has the characteristic appearance of coral. Celluloid gives off a camphor odor when it is heated. Wood can be scratched by the fingernail, exposing the wood texture under the artificial surface. Sealing wax has a flowed, glasslike appearance under magnification. If necessary, hydrochloric acid may be used to distinguish these substitutes, since none of them effervesces, in contrast to coral, conch pearl and conch shell.
The value of coral varies widely, according to the color and size of
the pieces. Those who work closely with it are said to be able to
recognize at least one hundred different tones of red. Gem material must
be compact, capable of taking a good polish, and free from spots, The
value of the various colors in America varies with fashion. For many
years, dark red was the most desirable and valuable type; later a vogue
for pale tints developed. Sometimes, coral is bleached with an acid or
stained with a dye to produce darker colors; usually, however, it is
used in its natural state. Racial custom, too, has a material effect on
relative local value, as evidence by the Arabs long standing preference
for the bright-red shade. Of perennial popularity in Europe is a rose
color that is known to coral dealers as "pelle d'angelo" ("angel's
skin"). Other descriptive terms that are or have been, commonly employed
are "bianco" (pure white); "rosa pallido" (pale rose); "rosa vivo"
(bright rose); "rosso" (red); "rosso scuro" (dark red); which is
also called "ox blood", "secondo colore" (second color); and finally the darkest red of all, "carbonetto," or "arciscuro". These terms originated in Italy, the past and present center of coral fishing and carving.
Current prices for fine quality rough material range between $80 and $160 per pound. In the late 1950's, finished bead necklaces of superior quality and workmanship with approximately eight-millimeter center beads and five-millimeter end beads brouqht from $400 to $2400 for the "ox-blood" color and up to $5000 for the finest "angel's-skin" type (all prices wholesale). Blemished, cracked, spotted or dull beads, of course, would reduce these prices considerable.
Trade terms sometimes used to designate various qualities include Japanese coral (pink with white centers), "tosa coral" (average quality Japanese material), "mora coral" (fine-quality light purplish-red Japanese material), Italian coral (good quality white to red pieces), Sardinian coral (excellent quality and very hard), Sicilian coral (inferior quality), and Algerian coral (less valuable gem quality).
As mentioned above, the fishing and working of coral is almost entirely an Italian industry. Fishing is invariably done during the summer months, since the winter storms increase the hazards to both men and cargo. The boats, built specifically for the purpose, are all constructed along the same lines and, even though comparatively small, they are solid and seaworthy. Little difficulty is experienced by the divers in shallow water; in areas of greater depth, however, from which the finest material is obtained, special apparatus is required.
Coral is most commonly fashioned into beads, either round or egg shaped, and used in the manufacture of necklaces, rosaries and bracelets. Carved ornaments, including cameos and intaglios and figurines, are frequently seen-beautifully intricate pieces that represent the height of the Italian craftsman's art. An outstanding example is shown in the accompanying photograph. Other carvings may represent such familiar objects familiar objects as trees, birds and animals; even pieces of sufficient size for umbrella handles and walking sticks have been carved.
Color is the principal attraction of coral, and it is to this factor
that particular attention should be given. With the wide color range at
the salesman's command, the possibilities for using coral as accent or
contrast mediums is unlimited. When combined with turquoise in a piece
of jewelry, for example, it is particularly charming for wear with
pastel tints. Pink should always be of interest to blondes, and the deep
red and white are appropriate for brunettes. A salesman who is
interested in selling coral would be wise to become familiar with
sources of the proper lipstick and fingernail polish to go with coral,
since it has been found that the fashion in lipstick and in coral are
not always coincident. In the past, coral has suffered because of the
inability of potential wearers to find these essential commodities.