Natural onyx stone is a variety of layered chalcedony, same as agate.  A lot of crystals fall into the two categories of agate and jasper.  Agate and Onyx differ in one important way.  Agate has bands that are kind of chaotic whereas Onyx has bands that are parallel and well, sensible. 

Agate and onyx are at least a little bit translucent and jasper is not at all.  Hold the crystal up to the light.  Does light come through it?  Then it is an agate or an onyx.  They all contain quartz, but in agates it is teeny tiny grained or microgranular quartz.  Agates and onyx also contain chalcedony that formed as layers or bands.  Sometimes the slab of agate or onyx used to cut the crystal, such as an onyx gemstone, had a band so vast that the cut piece is just one color.  Most agates and onyx are the results of volcanic rocks. 

If the color of the band is red or reddish brown, it is called sardonyx.  

Onyx stone meaning: 

The word onyx in reference to genuine onyx stone or onyx jewelry is a Latin word borrowed from a Greek word that means fingernail.  This is because they had a lot of onyx that was sort of olive skin color with a white band.  Onyx has been used to create onyx stone jewelry, (especially cameos), knife handles, pedestals, and carved for official seals and inlay work.

Onyx stone astrology is often associated with the sign of Cancer, but it is the official birthstone for Leo.

Onyx healing properties:  

Onyx is used for abscesses, alimentary canal, armpits, asthma, belching, breast cancer, coughing, diaphragm, digestion, elbows, esophagus, flatulence, gastritis, heartburn, hiccups, indigestion, lower lobes of the lungs, pancreas, sclerosis, stomach, thorax, ulcers, upper lobes of the liver and uterus.  To access the most of onyx stone healing properties, place your piece of jewelry in a glass of water and sit it in the sun for an hour, then remove your jewelry and drink the water.  Be sure the glass is plain without any decoration.  You can also pour the water into a bottle that you keep on hand so that you can pour a little into all of your beverages throughout the day.

Other onyx stone benefits are feelings of comfort and soothing.

Sardonyx healing properties:  vitality, courage and the ability to attract the resources needed, whether they be things, situations or people.  Eases situations with competitive people.  And those who compete should put on their red onyx jewelry.

Onyx metaphysical properties:

It has been long thought that onyx protection or protective powers comes from the love vibration it emanates.

Other onyx stone properties:

Excellent for leaders who profess love, compassion and forgiveness.