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Sard
Sard is silicate (chalcedony), SiO2 (cryptocrystalline). In the hand, it rates 6.5 to 7 on the Mohs scale, and it runs brownish red and chestnut. Uniform translucent brownish-red chalcedony, darker and browner than carnelian, glowing deep red-brown when backlit. Gravels and volcanic terrains; historic sources in Anatolia (ancient Sardis), India, and Brazil.
The geology.
Sard carries the formula SiO2 (cryptocrystalline). It belongs to the trigonal (cryptocrystalline) system. It is classified as silicate (chalcedony).
It sits at 6.5 to 7 on the Mohs scale. The surface reads waxy to vitreous on polish. Light behaviour is translucent. Specific gravity runs 2.58 to 2.64. The streak is white. It breaks with conchoidal fracture.
Uniform translucent brownish-red chalcedony, darker and browner than carnelian, glowing deep red-brown when backlit.
You will most often meet it as cabochons, carved intaglios, beads or tumbled.
The origins.
Gravels and volcanic terrains; historic sources in Anatolia (ancient Sardis), India, and Brazil.
On value, the database notes: affordable; fine antique-style intaglio material runs higher.
Traditional associations.
In energy work traditions, associated with courage, stamina, and protection on long efforts.
People buy on this language, so it belongs on the page. It belongs under the facts, though, not over them.
Spotting the real thing.
Uniform translucent brownish-red chalcedony, darker and browner than carnelian, glowing deep red-brown when backlit.
Much commercial 'sard' and carnelian is heated or dyed agate from Brazil; banding under backlight gives treatment away.
| Looks like | How to tell them apart |
|---|---|
| Carnelian | Carnelian is brighter orange-red; sard is darker chestnut brown, the two grade into each other |
| Red jasper | Jasper is fully opaque even on thin edges; sard transmits warm light |
| Dyed agate | Heated and dyed material may show banding or color concentrated near the surface |
At-home tests.
You can run every one of these at a kitchen table. Good light matters more than gear when you are looking at sard.
| Test | What you should see |
|---|---|
| Scratch check | Scratches glass (Mohs 6.5 to 7) |
| By eye | Backlight shows translucent red-brown body |
| By eye | Color is even, without jasper's grainy opacity |
Destructive tests belong to a gemologist, not a kitchen table. If a piece matters to you, pay for an appraisal before you take a file to it.
Care & handling.
At 6.5 to 7 on the Mohs scale it handles careful wear but scratches against quartz and dust. Store it separately and take rings off before rough work.
It breaks with conchoidal fracture, which is worth knowing before you set it or drop it.
Clean it by hand, dry it properly, and keep it away from ultrasonic cleaners and hot steam.
A deeper look.
Extended detail on composition, sourcing, authentication and market value.
The physical record
The formula on record is SiO2 (cryptocrystalline). Crystal system: Trigonal (cryptocrystalline). Specific gravity: 2.58 to 2.64. Streak: White. Cleavage and fracture: Conchoidal fracture.
How it reaches the market
Gravels and volcanic terrains; historic sources in Anatolia (ancient Sardis), India, and Brazil.
What it gets confused with
Carnelian: Carnelian is brighter orange-red; sard is darker chestnut brown, the two grade into each other. Red jasper: Jasper is fully opaque even on thin edges; sard transmits warm light. Dyed agate: Heated and dyed material may show banding or color concentrated near the surface.
What it is worth
Affordable; fine antique-style intaglio material runs higher.
Where buyers get caught
Much commercial 'sard' and carnelian is heated or dyed agate from Brazil; banding under backlight gives treatment away.
One more thing
Sard was one of antiquity's favorite signet-ring stones because hot wax does not stick to polished chalcedony, Roman seals in sard survive by the thousand.
An education-first guide.
We do not stock sard. Writing it up regardless is the point of a reference library.
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