PRESIDIUM Gem Tester II Mode D'emploi page 15

Tips for using your Presidium Gem Tester II
If the tester is being used for the first time, or if the tester
has not been used for a week, it is advisable to clean the
probe tip using a piece of paper to attain consistent and
accurate reading. Rub the tip gently across the paper
surface before testing.
The probe tip must be placed at a right angle or
perpendicular to the facet of gemstone for an accurate
reading.
Tests should be conducted on the table of the gemstone.
In the event of any doubt, kindly test on the girdle of the
gemstones instead.
To achieve optimum accuracy for tests involving very
small gemstones (10 points and below), it is important
to allow the gemstone to cool down before subsequent
tests.
It is advisable to take multiple readings regarding the test
results indicated.
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