DISPOSITION OF ROUGH
In nearly every gemstone deposit, the truly useful material is a very small percentage of the whole, on the order of two to five per cent by weight of crystals which appear to be reasonably free of flaws, of good color, and of usable size. In order to make mining profitable, it is cus¬tomary among miners to adopt one of several schemes for selling their production. One method is to lump all of the production into a “mine run” lot, containing all grades from bad to good, and sell the lot in toto.

The other method is to grade the production at the mine and sell smaller lots at prices adjusted according to quality. The drawback to the first scheme is that very few buyers are able to pay for and dispose of large mine-run lots, forcing the miners to wait a discouragingly long time before the right customer comes along. The drawback to the second scheme is that buyers eagerly take top-grade rough but are reluctant to purchase lots of inferior material. Often the result is that the miners are “stuck” with considerable gem rough, which costs them as much to mine as the best grades, but for which there appears to be no market. If such miners had based their prices on the expectation of selling all grades, it is easy to see how their mining venture would become unprofitable. To avoid this disaster, miners usually place high enough prices on their readily saleable grades to assure themselves of at least recovering costs. Any further sales of poorer grades then become pure profit.

The same problem faces the field buyer who is usually headquartered in a large city, preferably with export facilities, and who sends his agents into the field to buy directly from the miners. Should he sell his pur¬chases “as is” or should he classify the rough into parcels of various grades? In some instances, the decision is easy because of the nature of the gem material itself, as in the case of the tigereye quartz from Griqualand in South West Africa which is remarkably consistent in quality and needs little sorting to be satisfactory to foreign customers. Other gem-stones, usually massive types, also can be sold in nearly the same con¬dition that they leave the mine, e.g., labradorite, amazonite, rose quartz, and rock crystal.

However, in a gem-producing region such as Minas Gerais in Brazil, where a bewildering variety of minerals and gemstones can be found in a single pegmatite, the field buyers purchase promising lots from the miners and ship them back to their city headquarters. Here the mine production is carefully washed and experts go over each piece, rejecting obviously unsuitable material, selecting suitable material, and placing the “doubtfuls” in a separate pile to be examined more closely at a later rime. Well-crystallized specimens that have escaped damage are examined critically. Those that promise to bring more as rough gem material are ruthlessly broken up, to the distress of the mineral-collecting fraternity, while those which promise to fetch a better price as specimens are set aside.

By the time the sorting process is over, the field buyer has a series of parcels of (a) top-quality facet material, (b) lesser-quality facet material, either poorer in color or containing flaws, (c) cabochon or carving ma¬terial, (d) specimen material, and (e) waste. While the dealer usually has no problem in disposing of all classes from (a) to (d), he realizes that his waste, if it can be sold, adds pure profit to his operation. If the waste consists of small chips, such as rock crystal, it can be sold to makers of fused quartz and glass; if it consists of colorful massive material or very small transparent gemstone bits, it can be sold to makers of tumbled gems who are thereby saved the trouble of crushing the rough material for themselves.
The above grades are not fixed by any means, and exceptional material may be placed in a “gem” category, usually a very small part of the whole, but so superior in quality and size that the sale of this one parcel may return the cost of the entire mine production lot. The same is true of large and fine mineral specimens such as undamaged crystals of beryl, tourmaline, spodumene, or topaz. Figure 1 shows Paulo Nercessian, a buyer of Rio de Janeiro, holding an enormous crystal of gem-quality kunzite which was saved out from a large quantity of other kunzite and sold separately as a unique museum specimen.

GEMSTONE MINING
Aside from the highly mechanized and efficient diamond-mining meth¬ods used in Africa, most gemstones are recovered from small pits sunk in gem-bearing gravel deposits or from short tunnels and shafts in hard rock. While extensive gem-bearing gravels containing rubies, sapphires, spinels, and other splendid gemstones occur in Ceylon and Burma, large quantities of topsoil and sterile gravel must be excavated before the layers containing gems are uncovered. After a pit is sunk with much labor and cost, the operators cannot be certain that they will find a productive deposit underneath. Continue Reading »

Supply and Marketing Information
A long chain of events marks the progress of rough gemstones from the time they leave the mine to the time they are placed before a buyer, transformed into brilliant objects of beauty. At each stage the parcel of rough is examined by an expert whose livelihood depends on the infalli¬bility of his judgment. Gradually the parcel is sorted out into various grades, from poor to superlative, and defective pieces removed. When at last the rough reaches the hands of the cutter it is subjected to the most critical scrutiny yet, for it is here that the promise in the colorful crystals is converted into gleaming, salable reality. The personal attention that each gemstone receives along the way contributes to the final cost and it is the purpose of this chapter to explain the workings of the system for the benefit of those who wish to deal in gems or wish to know how the gems they own came into being and why they are so costly.

NATURAL RARITY OF GEMSTONES
As mentioned before, most gemstones are minerals or rocks and occur in favored sites in the earth’s crust or in the gravels that result from the weathering of rocks. It is truly remarkable how little of the millions of tons of minerals exposed to our view consists of beautifully crystallized minerals such as might be useful for gems. Of those that seem useful for gems, only a very few actually meet the standards, that is, are sufficiently beautiful, durable, rare, and large enough to be cut into salable stones. As a class of natural objects, gemstones are exceedingly rare while rarer still are those which will produce first-class gems. Thus one of the factors that makes gems esteemed, rarity, is already an inherent feature.

SIZE
The use of the expression “bigger and better” summarizes this human factor. Increasing size in gems is symbolic of greater wealth and higher position, with some exceptions of course. Frankly, few persons can look upon a ten-carat diamond worn in an engagement ring without being impressed, especially if the engagement rings of their friends carry dia¬monds of only one carat or thereabouts. Continue Reading »

FASHION
The factor of fashion is closely related to those of attractiveness and rarity. What was considered attractive yesterday may not be attractive today, and today’s standards may be displaced by others tomorrow. Continue Reading »

RARITY
It is human nature to treasure the rare, sometimes for rarity’s sake alone. Among gems, for example, synthetic ruby has never been as highly esteemed as natural ruby because it is made in relatively enormous quan¬tities and is therefore much too common. On the other hand, synthetic star ruby, carefully controlled from manufacture to final retail sale in cut form, is able to command a good price because it is both beautiful and considerably rarer than ordinary transparent synthetic material.

While synthetic gems can be fully as handsome as their natural counterparts, natural gems of equal quality or even of much lesser quality find a ready market and sell for much higher prices. The preference for the natural is a highly important human factor.

Paradoxically, rarity, as will be shown, can be a handicap if it goes too far. It is well known among dealers in art objects, antiques, and jewels that before any person can appreciate the worth of a masterpiece, he must have pointed out to him all of the factors which make such an item desirable.

In the case of well-known gems such as diamond, ruby, sap¬phire, and emerald, nearly every prospective buyer has heard and read about them from childhood. By the time he becomes an adult, he has firmly fixed in his mind that these gems are precious, beautiful, and desirable. He has even accepted one gem, the diamond, as an indispensable part of the engagement ring. The average jeweler does not have to con¬vince the bridegroom-to-be that he should buy his fiancee a diamond engagement ring; this has already been done for him, and the sale nego-dations merely need to settle such mundane details as quality, size, and price.

This happy situation for the jeweler does not apply in the case of other gems, particularly if they are not well known. Thus, the transparent andalusite from Brazil, a handsome and durable gem, is readily salable only to connoisseurs or collectors of the unusual because it is so rare and its supplies so uncertain that no one in the trade wishes to risk a promo-donal campaign to acquaint the public with its virtues in the hope that profitable sales will result. Because of the problems briefly touched upon above, the vast majority of retailers in gems and gem-set jewelry avoid handling rare or unusual gemstones and stick to the “safe” standard gems which need no educational campaign to insure a supply of informed customers.

<p>DURABILITY
The ability of gems to resist normal wear while set in jewelry is a perfectly understandable requirement  and  needs no  supporting  arguments. Durability depends upon mineralogical hardness, or the ability to resist abrasion, and upon toughness, or resistance to fracture. Some cleavable minerals, such as topaz, while quite hard and easily capable of resisting normal abrasion, are sometimes split in two by relatively weak blows. Others, such as jadeite, whose single crystals are easily cleaved, occur in compact masses where this potential weakness is overcome by the interlocking of numerous minute crystals into a material of astonish¬ing toughness.
The generally accepted rule of thumb for classifying gemstones as durable is that they be as hard or harder than quartz. The table below shows the Mohs Scale of Hardness which is used for gemstones as well as for ordinary minerals. It merely indicates which gemstones are harder than others and does not give absolute hardnesses.

Mohs Scale of Hardness
1.    Talc (softest)    6. Feldspar: moonstone,
2.    Gypsum: satin spar,    7. Quartz: amethyst, citrine, etc. alabaster    8. Topaz
3.    Calcite: cave onyx    9. Corundum: ruby, sapphire
4.    Fluorite: “blue John”    10. Diamond (hardest)
5.    Apatite

Many authorities state that all gems will eventually be abraded by atmospheric dust and the traces of soil unavoidably brought into homes and buildings because these contain fine particles of quartz (hardness 7), and unless gems are harder than quartz, damage will result. However, the severity of this kind of abrasion has never been convincingly demon¬strated, and it is the view of other authorities that it is very minor in effect, if it has any effect at all, and that most damage to gems results from careless treatment while being worn, or from allowing gems to bump into each other in jewelry boxes or drawers.
While durability has its unchallenged virtues, exceptions to the rule are made if the gemstone happens to possess some other outstanding quality. Perhaps the best example is opal, which is both a soft and brittle mineral (hardness 5 to 6 1/4). It is so liable to damage while being worn that jewelers are frequently called upon to demount an opal from a customer’s ring and send it off for repolishing. Despite this handicap, opal commands very high prices in fine specimens because no other gemstone can match its distinctive beauty. Other soft and weak gemstones which are considered acceptable for wear because of their outstanding beauty are moonstone, peridot, and the synthetic gemstone strontium titanate.

FACTORS INFLUENCING ESTEEM
The factors influencing the esteem in which gems are held are few in number but extremely important because they so directly affect value. These are attractiveness, durability, rarity, fashion, and size. They are not fixed in scope by any means and the predominance of one factor may compensate for shortcomings in another.

ATTRACTIVENESS
The fascination felt for gems is mainly a visual appreciation of their beauty. There is little doubt that beauty is the most important quality that any gem can have, for without it no gem or other ornamental gem-stone object will be highly prized, regardless of what else it has to recom¬mend it. Beauty lies mainly in vivid coloration, as in the splendid red of the ruby or the glowing green of the emerald; it can also be in outline or shape, as in the symmetry of a well-cut faceted gem or the graceful lines of a tasteful carving; or it can exist in the special optical effects which the skilled lapidary is capable of developing in such gemstones as star sapphires, catseyes, or moonstones. Brilliance in a faceted gem is of course also highly important, especially if the sparkling reflections are combined with flashes of color in highly dispersive gems. All of these, and others too numerous to mention, influence the attraction we feel for gems.

COLOR
The importance of color cannot be overemphasized. It is one of the earliest impressions registered upon our senses when we fix our attention upon any object. Studies of human response to colors show that per¬ception of hue is best in the central part of the spectrum and decreases toward either end. Thus, yellow-green, yellow, and yellow-orange will appear brighter as a rule than the hues which range from yellow-green to violet, and from yellow-orange to red. Further, as colors are observed in the decreased light of evening, those at the extremes of the spectrum, namely red and violet, seem to become darker while those near the center tend to retain their visibility. In terms of colored gems, this means that dark red, blue, or violet gems are less likely to “hold” their hues in evening illumination than yellow, orange, or yellow-green gems. For the person contemplating buying expensive colored gem jewelry meant to be worn mainly at evening functions, it would certainly be wise to “test” the jewelry under the expected lighting conditions rather than under those so carefully provided in the jewelry store. Grave disappoint¬ments may be avoided.

An interesting sidelight to modern studies of color perception is that hues toward the violet end of the spectrum, the so-called “cool” colors, tend to depress spirits, while those toward the other or “warm” end of the spectrum tend to excite. These human reactions to color have been imply demonstrated in workshop and office environments and may pos¬sibly play important roles in personal acceptance or rejection of certain colors in gems.

The preference of individuals for specific colors is well established, but not so well known is the relative attractiveness of colored gems in general. The most attractive colors appear to be those which are pure and rich in hue, such as red, green, blue, purple, orange, and yellow. Of these hues, the first three are most attractive, while purple and orange are slightly less so. There is a substantial drop of interest in yellow. Interest also rapidly wanes in all hues which become increasingly darker or lighter. The least interest is displayed in gemstones which are some shade of brown, particularly if they tend to be quite dark. Black and white gemstones are also unattractive as a rule, although they may be in vogue for brief periods as evidenced by the lavish use of jet in the Victorian era. Colorless gems are generally unattractive unless, as in the case of faceted diamonds, they display good brilliance, preferably with good dispersion or “fire” as an added feature.

The presence of color is important even in those gems which are offered primarily for their display of optical effects, e.g., the sheen in moonstone, die spangles of aventurine, or the bright lines of reflected light which appear in star and eye stones. Between two moonstones, for example, one displaying a bluish light and the other a silvery light, the blue one will be preferred to the silvery one by the majority of persons. This preference holds true in virtually all kinds of lapidary objects, whether they be faceted gems, cabochons, or carvings.

Webster’s Unabridged Dictionary (Second Edition) defines a gem as “Any jewel, whether stone, pearl, or the like, having value and beauty that are intrinsic and not derived from its setting; a precious or, some-times, a semi-precious stone cut and polished for ornament.” Also, “A semi-precious stone of value because carved or engraved, as a cameo or intaglio.” Interestingly, below these definitions appears, “In modern usage, GEM more frequently suggests a precious stone as cut or polished; JEWEL, a precious stone as set and worn for ornament. . . .” Continue Reading »