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.