Dichroscope Analysis
Overview
The dichroscope detects pleochroism—the property of showing different colors when viewed from different directions. It's essential for identifying many colored gemstones.
How It Works
The dichroscope uses calcite or polarizing filters to split light into two polarized beams. If the gem is pleochroic, two different colors appear side by side in the viewing window.
Equipment Needed
- Calcite dichroscope or polarizing filter type
- Strong light source (LED or daylight)
- Dark background
Procedure
- Hold the dichroscope close to your eye
- Position the gem between the dichroscope and light
- Rotate the gem slowly while observing
- Note if one color or two colors are visible
- Check multiple orientations for strongest pleochroism
Typical Values / Results
| Gemstone | Value / Observation |
|---|---|
| Ruby | Strong: purplish-red / orangy-red |
| Blue Sapphire | Strong: violetish-blue / greenish-blue |
| Emerald | Distinct: bluish-green / yellowish-green |
| Tanzanite | Strong: blue / purple / green-yellow |
| Tourmaline | Strong: dark / light body color |
Limitations
Singly refractive gems (diamond, spinel, garnet) show no pleochroism. Pale gems may show weak effects. Orientation affects results.