Sphalerite is a soft and brittle mineral that can occur in a wide range of colours, most commonly in reddish, orange, yellow and brownish hues. Green, yellowish green, bluish green and colourless sphalerite is rare. It has a very high refractive index (RI) and an extremely high dispersion, which makes well cut sphalerite gems truly dazzling. Its hardness is 3.5 - 4 on Moh's hardness scale and it has 6 directions of perfect cleavage, which makes sphalerite unsuitable for most jewellery. If used in jewellery, sphalerite requires extreme care when setting and should be considered for earrings, pendants and broaches only.
The sphalerite offered on this page come from Mont Saint-Hilaire, Quebec. This locality is famous among gem and mineral collectors for its wide variety of fine minerals and rare gemstones. Many minerals species found at Mont Saint-Hilaire are found nowhere else on earth. While sphalerite gems are not unique to Mont Saint-Hilaire, the colours that occur here are very unusual.
These sphalerite gems possess an interesting property called triboluminescence, which can easily be seen during cutting. These gems give off visible light when they are being ground during the cutting process. This phenomenon is so strong that the light given off is easily seen even when the surrounding light is strong, but the effect even more dramatic when the lights are turned down or turned off. Unfortunately this only happens when the sphalerite is being scratched or ground away so it's not a feature you can see in these gems unless you destroy them, but interesting nonetheless.