Professional Jeweler Archive: Lilliputian Lily Pads

April 2000

Gemstones & Pearls/Gemology

Lilliputian Lily Pads

The second in our series on inclusions looks at a handsome characteristic in most peridots

Peer into the depths of a peridot and you’ll almost always be rewarded with an interesting view of a microscopic lily-pad inclusion. It’s a distinctive feature that helps to separate peridot from natural and man-made glass simulants.

It’s called a lily-pad inclusion because of its resemblance to the aquatic plant. Gemologically, it’s a disc-like stress fracture caused by crystals of another mineral in peridot, such as chromite, spinel or biotite.

The foreign mineral crystal generally lies at the center of the inclusion, and the fracture radiates from it in a disc-like fashion. In peridot from Arizona, fractures are known to occur also around negative crystals or voids.

These inclusions are best examined with a microscope using dark-field illumination (in which the gem is illuminated on all sides but is placed against a dark background for viewing).

– by Robert Weldon, G.G.

This peridot from Peridot Mesa, AZ, exhibits several lily-pad inclusions caused by negative crystals. The negative crystals are visible at the center of the discoid fractures at about 40X. Interestingly, the fractures in this peridot contain liquid droplets that cause iridescent colors to be seen in reflected light.

Copyright © 2001 by Bond Communications