Dichroscopy is used to investigate whether transparent, colored gemstones exhibit pleochroism, i.e. direction-dependent polychromy. This means that light rays passing through certain gemstones behave quite differently depending on which crystal system the stone under consideration belongs to. Some gemstones appear in different colours when viewed from different directions. Imitations frequently differ from natural stones because of this property.
Where do colours originate? Colors are only created in gemstones and precious stones when they allow part of the light to pass through or be reflected and absorb another part. A good example is the ruby: It acquires its striking red colour because it lets the red light and part of the blue light through or reflects it. The remaining colours of the visible spectrum are absorbed by the ruby.
Application & Function Dichroscopy
The light emanating from the stone to be examined is broken down by a calcite crystal inside the dichroscope into two adjacent light beams polarised perpendicular to each other.
In our example, the green light from a green tourmaline falling into the dichroscope. Here it is separated into two beams: a north-south oscillating “extraordinary beam” and an east-west oscillating “ordinary beam”. As the two rays were absorbed differently in the tourmaline due to their different vibrational directions, one appears in green and the other in blue-green color.
Video Pleochroism analysis with the dichroscope
Experience how the dichroscopy dichroscope in combination with a cold light source enables fast and precise gemstone identification – and helps to separate genuine natural stones from deceptively similar imitations. You will find various dichroscope models in the KRÜSS store.
You are currently viewing a placeholder content from YouTube. To access the actual content, click the button below. Please note that doing so will share data with third-party providers.
More InformationNote: The hand-held dichroscope is also a central component of ourlarge mobile gemstone laboratory, which stands for maximum flexibility. Each of the two mobile gemmological laboratories is equipped with high-quality, professional analytical instruments and enables precise investigations on the move – at trade fairs, at customers’ premises or directly on site.
Do you want to read more?
If you are looking for more specialist information, you should order the white paper “Gemstone Dichroscopy”. The following topics, for example, are described in the specialist publication:
- Design and mode of operation of a dichroscope
- Colour origin of a citrine
- How does pleochroism develop?
- Practical tips: How to examine pleochroism correctly with a dichroscope
- Colour Chart and Analysing Sheet for Colour
- Identification Distinguishing between amethyst and glass with the dichroscope
- Identifying emeralds by their multicolouring (dichroism)
- Pleochroism in tourmaline
- Observe pleochroism (trichroism) in a tanzanite crystal
The whitepaper was produced in collaboration with Prof. Dr. Jochen Schlueter wrote. a qualified mineralogist in charge of the permanent collection on display at the Mineralogical Museum in Hamburg.
Enter your contact details here and we will send you our detailed white paper on dichroscopy by e-mail.