01Decisive
Scratch a glass plate
Carnelian at hardness 7 marks glass; glass imitations do not mark each other. This separates the material from the commonest cheap substitute in one stroke.
Agate · Lovenhall Stone
How to Identify Carnelian
Orange to rust-red chalcedony, coloured by iron. Much of it is heat-treated, which is ancient practice.
Brazil, Uruguay, India, Mexico, Germany (Idar-Oberstein), Scotland
Carnelian is chalcedony coloured by iron oxide, running from pale orange through to deep brownish red. Heating intensifies the colour by converting the iron, and this has been done deliberately for at least four thousand years — Indus Valley and Egyptian carnelian was heat-treated, so this is not a modern shortcut but part of what the material has always been.
Natural and heated carnelian are both genuine, and separating them is difficult and mostly beside the point. What is worth separating is carnelian from dyed agate sold as carnelian. Hold the piece against a strong light: natural and heated carnelian shows a cloudy, uneven distribution of colour, often with faint banding visible, whereas dyed material tends to be more evenly saturated with colour concentrated along fractures.
The other common substitution is glass, which is separated by hardness — carnelian is 7 and scratches a glass plate, glass does not.
Model-specific checks
What decides a Carnelian
These apply to this model and not to the rest of Agate. Work them alongside the maker's general checks, not instead of them.
02Strong
Look through it at a strong light for cloudy uneven colour
Genuine carnelian's colour is patchy and often faintly banded when backlit, because the iron distribution is uneven. Dyed agate reads more uniformly saturated, with colour intensified along fractures.
The market
What a Carnelian does on the secondary market
Inexpensive. Tumbled pieces a few dollars; fine deep-red cabochons low tens.
An orientation for honest, unrestored condition — never an appraisal, and never a quotation.
All the Agate checks
Free tools of the room
Lovenhall StoneRead the stone itself
The tests tell you what it is. The instrument reads a photograph and offers a name to start from — then hands you back to the tile and the coin, which are what settle it.
Free on iPhone & iPad. An estimate, never an appraisal.
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