Foil Opal

Foil/Glass Imitation Opal

Consumer Information

What color is it?: As you can see above a quick look might fool consumers but experienced jewelers will know the difference almost immediately. Which is why consumers should stay with a professional jeweler when shopping for opals. These cheap imitations are easy to come by and sometime difficult to spot for the untrained.

What is the story behind this gemstone?: Just another gem material for consumers to worry about and gemologists to learn about. This one is made from glass and foil giving a somewhat close opal look if you are not careful.

Here's the rest of the story on this imitation opal......

Chemical: Si02 (

Formation: The real question is "why" rather than "how"

Crystal System: Amorphous

Unusual Properties: None

RI: Varies

Optical Character: none

Hardness: Varies

Specific Gravity: Did not waste my time.

Special Identification Properties: Foil inserts are product colors which are not normal for opal.

Gemological Identification

Primary Test: Inspection with a 10x loupe and light source

Cabochon cut foil-filled glass imitation of opal


Same stone under 30X showing distinct foil areas

Secondary Test: None needed if you own a loupe.

With greatest appreciation to:

Synthetic Imitation & Treated Gemstones by Michael O'Donoghue, Butterworth Heinemann, London, 1997, and

Gems Made by Man, Kurt Nassau, Gemological Institute of America, Santa Monica, 1980

Without whose excellent books on this subject these web pages would not be possible.

Please note: All photographs and all text on this page are © Copyright 2011 by

I prefer not to have to mess up the photographs with a bunch of copyright notices so please respect the copyright for the sake of everyone else who visits this site.

Back to Synthetic Study Main Page

Back to Home Page




Photo by YourGemologist