What Colours Can Ammolite Be?
Ammolite can display colours across much of the visible spectrum. Red, orange, yellow and green are frequently encountered, while some specimens also show blue and violet. A single piece can contain one dominant colour or a combination of several colours.
Just as important as the colours themselves is how they behave. The intensity of the iridescence, the number and distribution of colours, pattern and the way the appearance changes as the specimen is moved can all contribute to its visual quality. This means two pieces of ammolite from the same geological formation can look dramatically different.
Is Ammolite a Gemstone or a Fossil?
It is effectively both. Its origin is biological: the material comes from the shell of an extinct ammonite. But gem-quality iridescent shell is also cut, polished and used as an ornamental gem material.
Ammolite entered the commercial gem market comparatively recently, becoming established during the second half of the 20th century. The World Jewellery Confederation, CIBJO, recognised ammolite as an organic gem material in 1981. This dual identity is part of its fascination. An ammolite is not simply a colourful stone that happens to be old. Its colour survives within material originally produced by an animal living in a Cretaceous sea.
How Is Ammolite Used in Jewellery?
The colourful layer of ammolite is generally thin and can be fragile. For this reason, material intended for jewellery is often stabilised or assembled into doublets or triplets.
A doublet typically combines the ammolite with a backing material for support. A triplet adds a transparent protective layer above the ammolite as well. This construction helps protect the thin iridescent material while allowing its colour to remain visible. Treatments and construction should therefore be considered when examining or valuing ammolite jewellery.
Ammolite can be encountered in rings, pendants, earrings, brooches and other jewellery, as well as polished specimens retained principally for display.
What Makes Ammolite Valuable?
There is no single characteristic that determines the value of ammolite. Colour is an obvious consideration. Bright, vivid iridescence and an attractive combination of colours can contribute to desirability.
Brightness and iridescence matter too. Fine material can retain strong colour across a useful range of viewing angles rather than appearing impressive from only one position.
Pattern can distinguish individual specimens. Fractures and variations within the shell create distinctive arrangements of colour and texture. Size can matter, particularly when a comparatively large area of high-quality iridescent material survives.
Condition and treatment also need to be understood. Ammolite is naturally delicate, and jewellery may incorporate stabilisation, backing or protective layers.
For complete ammonite fossils displaying iridescence, the assessment can be different again. The quality of the fossil itself, completeness, preparation, provenance and overall presentation may all be relevant alongside the colour of the surviving shell.
Are Iridescent Ammonites Always Ammolite?
This is where the terminology becomes less straightforward. Iridescence is not exclusive to ammonite fossils from Alberta. Iridescent ammonites are known from other parts of the world, including Madagascar and Russia. GIA has noted that particularly fine material from Russia can display iridescence comparable with Canadian examples.
In the gem trade, however, ammolite has become particularly associated with the exceptional gem-quality ammonite material of southern Alberta. For collectors looking at complete fossils rather than fashioned gemstones, it can therefore be more useful to establish exactly what the specimen is, where it was found and how its shell has been preserved rather than relying on colour alone.
Ammolite and Iridescent Ammonites at Auction
Iridescent ammonites can be considerably more than decorative fossils. In June 2022, Lyon & Turnbull sold an iridescent ammonite from the Bearpaw Formation for £20,000 inc fees. An exceptional auction result like this should not be interpreted as a standard value for ammonites or ammolite. Complete fossils can vary enormously according to their size, species, preservation, iridescence, preparation, condition and provenance.
If you own an ammonite and are unsure whether it is significant, our guide to Ammonite Fossil Valuations & Selling at Auction explains some of the characteristics our Natural History specialists consider when assessing a specimen.
