Demantoid Garnet

Oval Demantoid Garnet

Demantoid Garnet
Demantoid garnet is a rare and beautiful bright grass green sub-variety of andradite garnet. It appears to have first been discovered around 1892 in the Bobrovka area of Russia.
The Bobrovka is a small tributary of the River Tschussowaja in the Sissersk region on the western side of the Ural Mountains.
It was at first thought to be emerald, which is found nearby, and has been erroneously called "Uralian emerald".
The name demantoid means diamond-like, because it has a very high adamantine lustre, and a colour dispersion higher than diamond. The only disadvantageous property of demantoid is its low hardness figure at about 6.5 Moh. It is the softest of the garnets, and is more suitable for use in brooches, pendants, or ear-rings, rather than rings, because of this.
The brilliant colour of demantoid garnet is due to partial replacement of the silicate by chromic oxide.
A diagnostic characteristic of demantoid is the inclusion of radiating fibres of byssolite (asbestos) fibres in a pattern described as a horse-tail. There is no other green stone which shows this feature.

A Victorian Favourite
In late Victorian times, and early in the twentieth century, demantoid became a very sought after stone. It commanded high prices because it has never been available in large quantity. In recent decades, it has been unobtainable as newly mined stones, and has only been available from antique jewellery.

Newly Available
Recently, small finds have again been made in Russia, and a small quantity of fine quality stones have recently come onto the market.
Gemstone lovers wishing to acquire a piece of demantoid garnet should take this opportunity to do so. If the current seams of demantoid run out, there may be another century without new stocks of demantoid becoming available.

Technical Information

Hardness	6.5
Refractive Index	1.888 to 1.889
Dispersion	0.057 3.82 to 3.85
Specific Gravity	3.55 - 3.67