All you wanted to know about gemstones
Welcome to our blog, here you can find many articles about gemstones, diamonds, expensive stones etc.
In 1940, these centers were over-run by the Germans, and the skilled craftsmen were obliged to flee as refugees to various parts of the world. England, the U.S.A., and Israel were among the countries which benefitted by the influx, and before long, the lapidary industry was established on a small scale in various new countries. [...]
For some years prior to 1939, an increasing number of Dutch and Belgian firms were sending a proportion of their rough material to. Idar-Oberstein, Briicke, Hanau, and to other cutting centers in Germany. Here, the work was done on a commission basis since labor was cheaper in Germany. But Antwerp probably cut the bulk of [...]
For polishing agate, lapis lazuli, turquoise, and malachite, beechwood rollers faced with soft leather are often used. These revolve at about 200 to 400 revolutions per minute. Chinese jade is polished with silicon carbide wheels, and lubricated with weak vinegar. Opal is best polished with leather discs coated with tripoli, which is really a finely [...]
The next operation is sawing, which divides up the rough material to the best advantage. Sawing may be necessary to obtain the largest possible stone from the given piece of rough if this is flawed, for cleavage might not obviate the flawed portion. This process is carried out by means of a thin copper or [...]
The cutting of diamonds is quite a separate industry from that of the cutting of the so-called “colored stones,” that is, the other precious varieties, and also from semi-precious stone work. Despite various developments and enterprises elsewhere, Antwerp and Amsterdam were by far the most important diamond cutting centers up to the year 1939, and [...]
Waste material from diamond cutting is used for industrial purposes, such as drills and polishing material. Diamond powder, which was originally the waste from the processes of cleaving and bruting crystals, was used only for grinding and polishing. But now it is considered to be the best abrasive on account of its great hardness and [...]
The period 1914 to 1918 was a difficult one on account of the lack of coal supply, but a solution was found in electricity, which power the entire industry now uses in Amsterdam. There was progress in the next twenty years, but 1940 saw a complete disorganization of the Low Countries on account of the [...]
It was not until the Fifteenth Century that the abrasive property of diamond used for manufacturing diamond engagement rings was discovered and used. The attempt to cut and polish this stone by any other stone or material had always failed, and naturally so, since diamond is the hardest substance known. Subsequently, the cleavage property of [...]
The Egyptians also knew of a method of drilling, which was effected by a tubular drill, a hollow copper tube, and this was rotated either by rolling between the hands or by means of a handle, an abrasive powder being used at the same time. A copper or stone point was also sometimes used, as [...]
Carbonado, which comes mainly from Brazil, is the toughest variety of diamond, but it is far less plentiful than boart. Corundum, when used as an abrasive, is dull gray or brown in color, nontransparent, and it is largely imported from the Transvaal. Much’of this is exported to the U.S.A. for use in grinding wheels.
Emery is [...]