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. Lighting 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 raw or cut – the different color reactions when looking through the respective color filter are decisive.
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DETECT AQUAMARINE COUNTERFEITING WITH THE CHELSEA FILTER
“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 a mythology, the aquamarine comes from a mermaid’s treasure chest and has a high symbolic power for purity, love and luck. Aquamarine has the ability to bring about color changes from light to dark and it 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 site in order 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).
If you want to know exactly how color filters are used to identify gemstones and gemstones and would like to find out details about well-founded examination examples, simply order our whitepaper “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.
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Here you can order the “Color Filters” whitepaper free of charge, in which many exemplary examination options with filters are described. 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.