Rubies (both genuine and synthetic) appear brilliant red under the filter. Synthetic blue spinel appear yellow-orange or pink while aquamarine and sapphires appear green or green-grey.
* Ensure the filter is kept clean.
* Do not leave the filter under or upon any hot object such as a radiator or lamp or in sunlight.
* Do not immerse in liquids.
* When the filter is not in use, fold the cover over the filter and place in the plastic bag.
* wipe dust from the filter with a soft dry cloth, or use a blower