Light passing through some crystals is absorbed differently in different directions. Commonly, different wavelengths of light (colors of light) are absorbed different amounts in different directions.

The color we see is the color of light after the absorbed wavelengths have been removed. Thus, if we absorb red light we see blue colors and if we absorb blue light we see reddish colors.

If red light is absorbed more in one direction that another, we will see that the stone looks bluer in that direction.

Thus, a consequence of pleochroism is that stones look different colors in different orientations.

Note that not all stones show pleochroism!

Note that the information below further illustrates the concept of pleochroism by providing examples but the information is NOT required for students of EPS 2

S,D,W,VW = strong, distinct, weak, very weak

Purple and Violet

Corundum (S)............violet / orange

Tourmaline (S)....light purple / purple

Amethyst (WD)....purple / reddish purple

Andalusite (S)..brownish-green/dark red/purple

Spodumene (Kunzite) (S).....violet/purple/colorless/pink

Beryl (DS)..............violet/colorless

Alexandrite/Crysoberyl(S)..red-purple/orange/dark green

Topaz (DS).........light to very light purple

Blue

Beryl (WD).........light blue /darker blue

Corundum (S)..dark violet-blue/light green-blue

Topaz (WD).............colorless/light blue

Tourmaline (S)........dark blue/light blue

Zircon (S)............med.blue/colorless/grey

Apatite (S)...............blue/yellow

Benitoite (S)..........colorless/dark blue

Iolite (S)..colorless/yellow/blue/dark blue-violet

Zoisite (S).....blue/violet red/green yellow

Zoisite (Heated) (S).....blue/violet/pink

Green

Emerald (S)...............green/blue green

Sapphire (S)..............green/yellow green

Tourmaline(S).blue green/dark brown green/yellow green

Zircon (W)................brown green/green

Topaz (D).................blue green/light green

Sphene (D)................brown green/blue green

Andalusite (S)............brown green/dark red

Alexandrite/Crysoberyl (S)...........dark red/orange/green

Peridot (W)...............yellow green/green

Yellow

Beryl (W)..........light green yellow/light blue

Chrysoberyl (D)...colorless/very light yellow/green yellow

Sapphire (W).................yellow/light yellow

Danburite (W).....very light yellow/light yellow

Phenakite (D)............colorless/orange yellow

Citrine (VW)......light yellow/very light yellow

Spodumene (D).....light yellow/very light yellow

Topaz (D)......brown yellow/yellow/orange yellow

Tourmaline (D)..........light yellow/dark yellow

Zircon (W)...................yellow brown/yellow

Brown and Orange

Axinite (S)

Sapphire (S)

Quartz (W)

Topaz (D)

Tourmaline (WD)

Zircon (WD)

Pink and Red

Andalusite (S)........dark red/brown red

Morganite (see beryl) (D).........light red/red violet

Alexandrite/Crysoberyl (S).......dark red/orange/green

Ruby (S)..............violet red/orange red

Rose Quartz (S).......brown red/light pink

Synth. Corundum (S)...violet red/orange red

Topaz (DS)............light red/yellow

Tourmaline (S)........dark red/light red

Zircon (D)............red purple/red brown