Description
While this gemstone filter was originally made as a Tanzanite filter, it can actually be used with many other types of gemstones in other ways.
This filter was created by Dr. Bill Hanneman to identify the differences between tanzanite and its simulants such as blue synthetic forsterite.
The stone is first inspected using the colour filter part of the device and then viewed through the London dichroscope part of the filter.
When the two parts of the filter are combined in this way, Tanzanite will give you a unique combination of reactions that are not observed with other simulants.
Genuine Tanzanite will appear reddish pink orange through the colour part of filter, whereas synthetic Forsterite exhibits a greenish body colour when viewed through the filter.
Genuine Tanzanite will also display purplish pink and then blue colours through the London dichroscope part of the filter as additional confirmation.
In addition to what has been discussed so far, I have also personally found the Tanzanite Filter will also strongly display the red colour in colour change gemstones such as with colour change Garnets and Zircons, as well as displaying a strong red colour in chromium reactive gemstones like chrome green Tourmaline.
I have also noted that SOME UV reactive gemstone will display a strong red colour through the Alexandrite filter, some examples of these are a UV reactive Sri-Lanka blue Sapphire, pink Sapphire, Ruby and Spinel appearing red through the filter as good or better than a Chelsea filter would display it.
At the time of listing this product on the Gemrock Investments website, we are the only supplier in Australia making these amazing gemstone filters available.
Tanzanite Filter and Dichroscope User Instructions:
Place loose stones table down on the white viewing surface that comes with the filter kit. Illuminate with a bright incandescent light source.
For very dark stones, use a strong light source very close to the stone, and for mounted stones, strongly illuminate from below.
Through the filter, the viewing surface should appear a dim pinkish grey colour. Now view the gemstone through the Tanzanite filter while it is being illuminated with a strong light source, noting the apparent colour of the stone when viewed through the filter.
Consult the reference table supplied in your Tanzanite filter set for filter colour and the expected dichroism colour alignments to assist you in identifying the gemstone.
The London Dichroscope part of the filter is used to detect dichroism in gemstones.
Dichroism is an optical property where a gemstone shows two distinct colours when viewed from different angles.
The advantage of using the London Dichroscope part of the filter is that you will see the change in colours just by passing the filter over the gemstone, it achieves this as it has crossed polarised filters fixed at different angles which achieve the same effect as viewing the gemstone at different angles.
To use the Dichroscope part of the filter, illuminated gemstone on the white viewing surface while holding the filter just above the stone – at least 14 inches from the eye. Move the filter from side to side across the black strip dividing the two transparent polarizing filters.
