The Nefrite  From the greek word "kidney".  Formula: Ca2(Mg,Fe)5[(OH,F) I Si4O11]2

This amphibole mineral contains silicates of Calcium, Magnesium and iron with traces of Fluorine, Iodine and Silicon; its hardness is from 6 to 6½ and its specific weight is between 2.90 and 3.03. Its look is dense and of a oilish surfaces when touched. It has a great variety of different tones, but the most common one is a green tone, which goes from a very whiteish green to a shiny dark green.     

Historically this stone is known as Jade of China and the most valuable variety is the Imperial Jade.

The Jadeite  Formula: NaAl[Si2O6]

A mineral of the piroxene group, containing silicates of Sodium and Aluminium with traces of Silicon. Its hardness is from 6½ to 7 and its specific weight lies between 3.3 and 3.4. When the basic components are mixed with Chromium, the nefrite is light green, when mixed with Copper and Iron it is dark green, in the combination with Manganese, Iron, Nickel and Cobalt it has a range of colours from a blueish green to exotic colours like lilac, purple and pink. Each variety has a cristal-like surface and is transparent, when cut in thin plates.

Historically this stone is known as Chalchiuhite, Quetzal Jade, Mayan Jade of Mesoamerican Jade.

The Cloromelanite  Formula: ClNaFe[Si2O6] (3)

Of a characteristic deep green, nearly black colour, containing silicates of Chlorine, Sodium and Iron, enriched by traces of Silicon and Aluminium and mixed with other piroxene minerals. Its harness goes up to 7.5 and its specific weight lies between 3.3 and 3.36.

Minerologically it’s a variety of jadeite with mixtures of Chlorine, which is the reason for its dark colour.