Fossilization Process

Ammonites were preyed upon by mosasaurs and other marine reptiles. The reptiles sank peg- like teeth into their shells extracting their squid shaped bodies to eat. The empty shell then sank to the sea floor, and was then buried in mineral rich sediment. During the fossilization process the sediment preserved the shell and enhanced the colors; to iridescent greens, reds, yellows and rare blues and violets.

In 1981 the International Colored Gemstone Commission recognized ammolite as a new organic gemstone. It is the rarest gemstone in the world. Only 1 out of 100 ammonite specimens is usable as ammolite. The ammolite fossils can be found in museums worldwide and range in size from 20 inches in diameter to 6 feet in diameter. Because ammolite isn’t very hard it must be treated like a pearl or opal.

Grading

Gem Grade	AA	A+	A	A-
Colors	3 or more	1 or 2	1 or Pale	Dark / Pale
Iridescence	Brilliant	Bright	Included	Dull / Dark
Chromatic Shift	Spectro	Di	Mono	Little
Rotational Range	360�	240�	180�	90�

Colors
... Gemstone ammonite can be found in any color known in nature or the imagination of man. It can also have an infinite array of color combinations in every square centimeter. The higher grades will either have a very strong, bright single color, or contain a range of bright colors drawn from a color spectrum vaster than a rainbow. Lower grade gemstones will show less vibrant colors in a more limited range. Generally, red/green is more common than blue or purple, but there are certain hues, like crimson, violet and gold, that are very rare and in high demand.

Gem Forms

... Ammolite is sold in three forms: naturals, doublets and triplets.
... Naturals are free-form cabochons with a non-coated hand-finish. They are backed by the original shale of the fossil and can range in size from 10 carats to 6 inches across! Priced by carat weight the backing thickness should not exceed 1.5 mm.
... Doublets are free-form cabochons that have been bonded to a backing.
... Triplets are constructed of three layers. A dark gray wafer of natural shale (1) sits below a layer of Ammolite (2). On top, there is a calibrated cap of optical quartz or synthetic spinel (3). This assures that the Ammolite gemstone shows the most brilliant flash as well as being durable enough to be worn as every-day jewelry.

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