Onyx Gemstone Guide

Onyx Gemstone

Onyx refers to a variety of chalcedony. It is made up of multicoloured bands and is formed in volcanic lava. Its bands are parallel to each other, unlike many other stones which may have much more chaotic and random patterns such as those of agate.


Onyx can have bands of every colour running through it. Black onyx is usually a mostly black stone with bands of colours running through it. The black onyx sold in gemstone jewellery is usually heat treated and enhanced to create a brilliant black stone. You may also find that agate dyed black is sold under the name of onyx.

Sourcing onyx

One of the main sources of onyx is found in Brazil. Uruguay, Pakistan, Sri Lanka, India, Hawaii and Madagascar all have notable sources of onyx.

Caring for onyx

Store separately in a soft cloth pouch to avoid damage and scratching to other jewellery. Onyx jewellery should be wiped clean with a damp cloth.

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