Which one to buy? Is 250 watt desirable (or 150 watt)? Is there one
that has a sodium light attachment? Anyone want to offer advise on
how to prepare for the 20 stone exam?
Fiber optic light is useful from time to time but it is not
necessary for 20 stone test. Moreover, it can reveal the information
about the stone which can lead the beginner to a wrong conclusions.
The best way to prepare for the 20 stone test is always remember
that it is combination of all the properties of the stone which makes
identification possible. Do not concentrate on a single fact, no
mater how revealing it may appear. Always consider all the
observations about the stone as a whole. When all the facts would
point in a certain direction, that will be the right one.