Porous stones are the easiest to treat, for they will naturally absorb any coloring matter in the form of a solution much more readily than others which have a hard texture. Such stones would not be visibly porous and their surfaces might appear to be hard and smooth. Those of a crypto-crystalline structure seem to take an artificial stain the best, for instance, chalcedony and turquoise. Staining by the introduction of coloring matter almost always involves heating the specimen as well, so it will be seen that a controlled heat is a necessary factor in this process. Experience in judging the time and the amount of heat required is necessary; gradual application is essential, otherwise the stone will crack with the sudden and unequal expansion, and flaws will develop to such an extent that the material will be spoiled. With experience, the facility with which a rough stone will take a stain and the time required for the process can be approximately judged, and with some qualities of chalcedony, those which are most suitable for staining gain a higher price in the rough than others which are not so suitable for this purpose.

Chalcedony, a type of quartz which comprises several well known semi-precious stones, is most frequently used to produce an artificially colored but real stone. All colors are introduced, blues, greens, reds, pinks, and yellows, the blues and pinks usually being the most unstable. The translucent bluish material is sold as “chalcedony,” and the pink stones as “rosaline.” Both fade fairly quickly and unevenly, and a bead necklace of such stones will show differences of shade after wearing for a short time. The translucent greens, often of a very attractive shade, are more stable; they are marketed as “chrysoprase” or “green carnelian,” both misnomers, for there is a natural chrysoprase of a green color (always different from the artificial green), and green carnelian is a contradiction of terms. These stones are stained after cutting, but “chalcedony” and “rosaline” are stained in the rough before cutting.

Up to 1939, agates and large pieces of rough stone were still worked in mills which dot the sides of the winding river Nahe. The flowing water is diverted near the mill to form a pond, and by a system of sluices, it is controlled to fall on to a large flanged wheel. This mill wheel is thus revolved by the power of the water, and another system of pulleys and belts from the wheel transmits the power to the cutting and grinding stones within the mill itself. The water is then directed back to its normal course, where it joins the main stream on its downward path. A number of stone cutting mills which border the river at intervals are thus served by the same water.

The mills are run on a co-operative system, one man being elected the foreman by the workers, who might number up to ten. The foreman deals with the merchants, who give him a certain weight of rough stone with directions as to what they require to be cut. Payment of the work is shared out on a prearranged basis, the cut stones being returned to the merchant when ready. In a few instances, it has occurred that some of the rough stone not used has been retained by the workers, with the result that cut stones at a cheap price find their way on to the market, thus leading to undercutting. The men work together and buy their own equipment, such as wheels, laps, and belts, and also rent the small hut and often a piece of adjoining ground. If necessary, they can easily get an advance from a merchant or a bank for the purchase of necessary materials. Slitting, grinding, polishing, and drilling are all separate and different operations, sometimes being carried out by different mills. Drilling is always done by one who specializes in this craft, often at home in one room set aside as a workshop.

For the sake of convenience, the stones or beads to be drilled are first set in rows on a stone slab by means of a hard wax. When drilled, these stones are knocked out of the wax with a hammer. The top of the drill is fixed in one of three holes previously drilled in an agate slab, which is held by a wooden arm. Around the arm, passes the string of the bow, about 18 inches in length. The bow is worked forwards and backwards in a horizontal direction with the right hand, the wooden arm holding the drill passing under the left arm so that pressure on the drill may be controlled. Before commencing the drilling, the surface of each stone must first be slightly roughed off or drilled in the correct position with a larger hand drill. In this drill, the diamonds would naturally be set farther apart in order to make a larger hole.

If a bead be examined, it will be seen that the bored hole will be slightly larger at the surface. While working, a fine oil is constantly applied with the forefinger to the drill so that it will not bind or get too hot. The drill must be worked straight and true, and the hole is carried straight through the material unless it is thick, when it must be worked from both sides so that it will meet and make one straight line. If the drill holes do not meet exactly, they will leave a sharp edge within the bead, and this will cause cutting and fraying of any stringing material when the beads are eventually graduated and strung as necklaces. Moreover, the beads will not hang true, an irregularity that will be quickly noticed. The work is tiring and monotonous, and if care is not exercised, the drill will be broken in the material.