Spot fakes with color filters

Color filters allow observations in the range of special wavelengths, e.g. in the red range at 690 nm and in the yellow range at 570 nm. Looking through the filters lets some stones appear in a different color and helps to distinguish between gemstones and ornamental stones. Illumination with a strong, white light source, such as a cold light source, is important. The Chelsea filter and the ruby filter are preferred for gemstone examinations. They are particularly suitable for differentiating between different gemstones viewed together, for example for checking a gemstone lot. Stones such as garnets, emeralds or aquamarines can be rough or polished – the decisive factor is the different color reactions when viewed through the respective color filter.

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DETECTING AQUAMARINE COUNTERFEITS

“Aquamarine” is literally translated as “water of the sea”. The more intense and transparent the blue, the more valuable it is. A 22.14 carat aquamarine from Brazil from the Ceará region – with an octagonal faceted cut in an eye-clean, intense light blue – is currently being traded for around € 17,600. According to mythology, the aquamarine comes from the treasure chest of a mermaid and has a high symbolic power for purity, love and happiness.

The Chelsea filter is used for the investigation: aquamarine has the ability to cause color changes from light to dark and is assigned the ability to distinguish between true and false. The color filter is often a good help for the technical differentiation of blue stones. One example of this is the gemstone lot of raw aquamarine stones from Zambia. Light blue fluorites were added to the solder at the Place of orgin to simulate a higher carat weight. The “fake” stones can be clearly distinguished from the aquamarines in color under the Chelsea filter. The view through the Chelsea filter reveals the fake stones (yellowish) under the aquamarines (green).

Investigating red gemstones with the ruby filter

The ruby filter makes selected gemstones appear in a different color thanks to its specially colored glass. Under the ruby filter, only those stones that contain chromium glow an intense red. The ruby filter is also ideal for doublets or triplets and glass imitations quickly.

A particular highlight: synthetic emeralds from the flux process appear under the ruby filter in a strikingly intense red. This immediately raises the suspicion of a synthesis – and shows when further gemmological investigations make sense.

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Ruby filter investigation in practice

The ruby filter is an extremely useful screening tool for the initial assessment of red gemstones. In his latest information video, gemmology influencer Dimitri Zlatev shows how the ruby filter from KRÜSS Gemmology is used professionally. Illumination is provided by the KRÜSS Optronic cold light sources.

All of Dimitri’s videos can also be seen on our YouTube channel.

If you want to know exactly how color filters are used to identify gemstones and precious stones and would like to find out details about technically sound examination examples, simply order our white paper “Color filters”. This specialist publication 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.

Do you want to read more?

Here you can order the free white paper “Color filters”, which describes many exemplary examination options with filters. Simply enter your contact details here and we will send you our detailed white paper as a PDF on the subject of “color filters” by email.

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