74 - The Colors Balas, Ruby, Topaz, Opal, and Girasol in Rock Crystal.
Take orpiment of that really tawny orange-yellow color and pulverize 2 ounces of this along with 2 ounces of powdered crystalline arsenic [ skull ], 1 ounce of pulverized crude antimony, and 1 ounce of sal ammoniac. Mix these powders thoroughly and put them into a very large crucible. Over this powder put shards and small pieces of crystal. Over that, you should put more pieces of larger crystal, which are spotless; like limpid pools in their clarity. lf you want to do something really nice, fill up the crucible with very large pieces.
Now, put another crucible over it positioned mouth to mouth. Then cement them very well, having first made a hole the size of a coin in the bottom of the upper crucible. Do this so the air will draw the fumes of the materials from it and will pass through all of the crystals, and tint them well; better than if the fumes just passes through the joint between the crucibles.
Once the lute dries, position the crucibles, burying the bottom one and half of the other under coals. Then kindle the fire little by little, and as the coals begin to burn, leave them then to ignite each other, until the fire engulfs them all. These coals should be made of large pieces of hard oak. Leave them to burn, and if they do not catch then blow on them so that the fire fully ignites.
Perform this entire operati011 under a large chimney to draw the fumes out of the room. These fumes are not only harmful but also quite deadly. Return to see if the coals have died down, because for the work to come out nicely, they must be burning well and full. For the remainder, leave and let the fire run its course with no one in the room with the work, for it is dangerous; the harsh materials will smoke quite a bit [ ]. Leave it to finish all fuming by itself and then extinguish the fire and spread the coals.
Make sure not to expose the crucibles to wind or cold breezes from windows or other places, because this would make the hot pieces of crystal crack, and break, and become unusable. When everything is cool and the crucibles are again cold, take them and remove the lute.
Most of the crystals will be timed the true color of topaz, chrysolite, balas, ruby, girasol, and opal, which look wonderful. At the wheel, jewelers may work and polish those pieces with the best coloration and tint. They mimic natural gems with their lustrous colors and natural beauty. Better still, these crystal imitations retain their previous natural hardness, which as you know is considerable.
In Antwerp, I made quite a bit of this, and there some ranged in tint from an opal color that looked very beautiful, to a girasol, similarly nice. These stones worked in various ways will be a sight better than ordinary. If you set them in gold with foil, much as the natural stones, you must use orpiment of that beautiful golden hue rather than brown.
Herein lays the whole secret, because the other orpiment, which has a lot of contamination and a sallow color, will not work well. The fire must be kept slow at first, and left alone to extinguish itself, and fully cool. Using these guidelines, the work should come out beautifully. lf you do not have good success the first time, then repeat it a second time to gain practice; from then on, you will do it without fail.