Fakt

Alexandrite is a natural variety of the mineral chrysoberyl with an admixture of chromium. It was first described in 1842. It differs from other, as a rule, yellowish-green chrysoberyls by its strong pleochroism.

Pearl - a mineraloid, a biogenic solid, rounded or irregular shaped formation, extracted from the shells of some marine and river mollusks. The formation of pearls is a protective reaction of the mollusk body to any foreign body caught in the mantle or between the mantle and the shell.

Opal is a mineraloid, SiO?-nH?O amorphous silica, widely used in jewelry.

Topaz is a semi-precious stone, a mineral of the group of basic aluminum silicates. It crystallizes in rhombic syngony, rhombo-biramidal type of symmetry.

Moonstone is a relatively rare mineral of the potassium feldspar group, a type of low-temperature orthoclase. It is named for its shining blue iridescence, which is caused by its thin-plate structure.