Accompanying value information:
The International Gem Society (IGS) has a list of businesses offering gemstone appraisal services.
Ammolite “naturals” are freeform cabochons with a non-coated hand finish. They’re backed by the original shale of the fossil and can range in size up to 10 carats and 6 inches across. These are priced by carat weight, but the backing thickness shouldn’t exceed 1.5 mm.
Gem cutters can also create ammolite doublets or triplets. Doublets are freeform cabs bonded to a backing. Ammolite triplets are usually constructed on a dark gray wafer of natural shale (1) below a thin layer of ammolite (2). On top, there’s usually a calibrated cap of optical quartz or synthetic spinel (3). This structure allows the ammolite to show the most brilliant flash while protecting it in a setting durable enough for everyday jewelry wear.
The ammolite industry has yet to agree on any one grading system. However, most systems refer to color, brightness, iridescence, etc.
|Colors||3 or more||1 or 2||1 or Pale||Dark/Pale|
For more information on ammolite quality factors consult the IGS buying guide.