Hard and soft precious stones

Hard and soft precious stones

However, there is another division, which is worth writing a little more about. We will refer to it frequently in later chapters. “In this case, the hardness of the stones was chosen as the criterion.

As it should be …

Precious and semi-precious stones

Precious and semi-precious stones.

We have already mentioned many names of gemstones, So it's time to think, how many of them exist at all and can they be systematized in some way.

Specialists have already counted over 300 stones, and this number is constantly increasing. …

Crystals and their structure

Crystals and their structure.

Already in antiquity it was noticed, that a common mineral called quartz can exist in the form of polyhedrons bounded by flat faces. These polyhedra constantly have the shape of a hexagonal column ended with the walls of the pyramids. Although the individual geometric forms of quartz differ in appearance, constant …