silicates
Andradite
Ca3Fe3+2(SiO4)3
- Also known as
- demantoidmelanitetopazolite
- Crystal system
- cubic
- Hardness
- 6.5–7 on the Mohs scale
- Lustre
- adamantine
- Colour
- Green, yellow, brown, black
- Where it forms
- In metamorphosed limestones and in serpentinites, and in skarns where igneous intrusions have altered carbonate rock.
- Chiefly from
- Ural Mountains, RussiaNamibiaMadagascarIran
Why it is that colour
Chromium gives the green of demantoid; titanium gives the black of melanite; iron gives the general yellow-brown.
Safety
Safe to handle.
Where it comes from
Russian Ural demantoid from the Bobrovka river has been worked since the 1850s. Namibian and Madagascan material supplies most current production.
Historical use
Demantoid has higher dispersion than diamond — it splits white light into spectral colours more strongly — which is where the name comes from, meaning diamond-like. It was a favourite of Fabergé.
Recorded as history and attributed where possible. That a stone was used for something establishes that people used it, not that it worked.
What is attributed to it, and since when
Named in 1868 after the Portuguese mineralogist José Bonifácio de Andrada. No pre-modern attribution.
Described, not endorsed. Dating a claim is not the same as assessing it — but an association that first appears in a book published in 1985 is not an ancient inheritance, whatever the label says. A sincere account of feeling better is compatible with the stone doing nothing — see the placebo effect.
Worth knowing
Demantoid is one of the very few gems where an inclusion increases the value. Russian material frequently contains radiating sprays of fine chrysotile fibres called horsetails, and their presence both confirms the Ural origin and is considered desirable — the opposite of the usual rule that a clean stone is a better stone.
It is also, quietly, the highest-dispersion natural gemstone in common use. A well-cut demantoid throws more spectral fire than a diamond of the same size. It is rarely cut to show this, because it is usually too small.
Identity checked against IMA-CNMNC master list, June 2025.