Hi Ronald - I'm no expert on ornamental objects and I wouldn't be able to give you a guide on value. But if you would like to send on a few photos I would be happy to take a look and do my best on stone type for you .
Onyx and Agate: sister stones with a long history
Written by Jane on Aug. 08, 2022 | 2 Comments
Onyx and its sister mineral agate, are some of the oldest gemstones ever to be used in jewelry. Beads made from these stones have been found in the Indus valley dating to 5,000 years ago. Prized throughout history by ancient Egyptians, Greeks, Sasanians and Romans, these versatile and durable stones remain a popular choice for jewelry to this day.
An ancient Egyptian onyx bead
Photo Credit: Royal Museum of Art and History, Belgium
If you are thinking of adding a piece of onyx or agate jewelry to your collection, you may be interested to find out more before purchasing. Below is our guide to onyx and agate, where you will learn:
- What are onyx and agate?
- How are onyx and agate used?
- Why choose onyx or agate jewelry?
- How to care for onyx and agate jewelry?
1. What are onyx and agate?
Onyx and agate are both varieties of chalcedony, formed from tiny crystals of silica dioxide in the form of the hardwearing mineral quartz and the recently discovered, moganite.
Despite being essentially chemically identical, both agate and onyx come in a rainbow of colors arranged in characteristic layers. The only real difference between agate and onyx is how these layers are arranged. In agate, the bands or layers are typically curved.
Agate with curved bands of alternating light and dark green.
Photo Credit: Irina Iacob on Unsplash
While in onyx, any bands present are linear, arranged in parallel bands of alternating color of variable thickness. Popular forms of onyx, particularly for jewelry, includes reddish, brown and cream sardonyx, one of the birthstones for August babies.
Polished cabochons of sardonyx, a form of onyx with alternating red and cream bands
Photo Credit: Puclales
Black onyx with thin bands of alternating black and white are also highly prized and expertly worked since the time of the ancient Romans. But entirely black onyx with little white is exceedingly rare in nature. Black onyx used in jewelry today is typically treated to ramp up rich deep back shades.
The Gemma Augustea, an ancient Roman cameo expertly carved in banded onyx with a depiction of Emperor Augustus, now located in the Kunsthistorisches Museum, Vienna.
Photo Credit: James Steakley
2. How are onyx and agate used?
Onyx and agate hold the title for some of the oldest recorded use of gemstones in jewelry with beads of 5000 years old discovered in the Indus valley. But their hardness and durability also made onyx and agate a go to choice for ancient tools across the globe, including those associated with leather- working, mortars and pestles, arrow tips, as well as for ceremonial objects like knives and figures.
Onyx and agate were also often used to make seal impressions as hot wax does not stick to its cool polished surface.
Ancient agate seal with inscription and male bust found in modern day Iran
Photo Credit: Royal Museums of Art and History, Brussels, Belgium
With the advance of gem cutting tools and techniques, agate and in particular onyx was used for producing intricate cameos and their inverse, intaglios. With their natural layered structure, ancient engravers could manipulate these alternating colors to create reliefs that played with shadow.
A cameo of emperor Caracalla carved in black and white onyx
Photo Credit: Museums Basel-Country, Switzerland
Both stones also hold ancient symbolism. The ancient Romans believed onyx bestowed courage, ancient Greek sailors wore it in amulets to protect from drowning, while in Chinese culture it was considered grounding for its wearer. Renaissance Europeans wore onyx for eloquence and it was even used to give strength to expectant mothers in childbirth. This precious stone continues to be treasured today as many wearers believe it brings feelings of reassurance, courage and determination.
Agate was equally prized for its protective powers, and it was considered especially lucky. Believed to bring harmony, health, and protection, green agate continues to be worn by many today for luck and as an aide for concentration and balance between body and mind.
3. Why choose onyx or agate jewelry?
Onyx and agate are versatile
With a rainbow of colors available, these stones can be faceted, carved, used as inlay or made into polished cobochons. The deep color of onyx in particular combined with the high reflectance of polished surfaces, makes them a wonderful choice for inlay, accent stones or center stones in their own right.
Onyx and agate are durable
Onyx and agate are relatively durable stones, especially when polished, with a Mohs rating of 7. Despite having lower hardness than precious minerals like diamond or sapphire, with no natural planes of weakness (cleavage) and a tough tenacity, they are some of the hardest wearing gemstones around and can resist most scratches, chips and even physical blows. With care, a well made piece of onyx or agate jewelry can be worn daily and passed on as a treasured family heirloom.
This hard wearing nature also makes them a smart choice for mens jewelry. They can stand up to wear and tear surprisingly well.
Onyx and agate are affordable
A piece of jewelry adorned with an onyx or agate accent stone comes in at a significantly more accessible price point than those adorned with sapphire, ruby, emerald or diamond.
Onyx and agate for anniversaries
Onyx and agate are also associated with wedding anniversaries. Onyx is a gift for the 9th year while agate is the stone to mark the 14th year of marriage and again for a substantial 39 years together. But we think adding a striking piece of stone set jewelry to your jewelry collection really needs no other reason than it makes for attractive and wearable pieces.
4. How to care for onyx and agate jewelry?
If you already own a piece of lovely onyx or agate jewelry or are thinking of buying and are wondering about how to keep it looking its best, here are our jewelry care tips.
Onyx or agate stone jewelry benefits from regular care and maintenance just as with any piece of fine jewelry. You can read our general jewelry care tips here.
Citrus fruit and vinegar cleaner - household materials that should not come in contact with jewelry.
Photo Credit: Precious Plastic Melbourne
Avoid contact with chemicals
Despite impressive hardness these stones can be vulnerable to chemical damage. Their finely crystalline nature means some liquids can penetrate and potentially react so be sure to keep them away from any chemicals including: cosmetics, hair spray, perfume, and common acids like lemon juice, or vinegar. Agate and onyx can also scratch against materials like diamond or sapphire so be sure to store it safely away from other jewelry.
Onyx and agate jewelry from My Irish Jeweler
You are now well on your way to becoming an onyx and agate expert. We are proud to offer our customers a beautiful selection of stone set jewelry designed and made here in Ireland.
So if you are thinking that a stone set piece might be for you, have a look at our selection or get in touch by email, phone, or by booking a virtual appointment. We would be delighted to answer any questions you might have.
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Jane
My Irish Jeweler
Born in Dublin but reared in Canada, as a child I had an interest in Ireland that will be familiar to many young emigrants. I was completely fascinated, wanting to know all about the land of my parents and grandparents. Rare month-long family trips back "Home" cemented my love for Ireland. And I wore my Irish heritage with pride, sporting my tiny silver Claddagh gifted to me by my Irish grandparents until my finger grew too large for it!
As a young adult I moved back to Dublin, studying Geology and Mineralogy in university at historic Trinity College Dublin. After living in Denmark and the Netherlands working as a scientist and university mineralogy lecturer, I finally settled back home in Dublin. I joined the growing family at My Irish Jeweler in 2016, bringing my useful knowledge of metals and minerals as well as my perspective as an Irish emigrant with a love for HOME.
Comments
Ask Gemma
Hi,
I was gifted a variety of prices from vases to eggs made of what I believe are marble, agate or onyx. I was hoping you could point me in the right direction or be able to identify there make or worth