6
GIA Polariscope
7
GIA Polariscope
Parts List
The GIA Polariscope includes the following items:
a)
Polariscope with built-in power supply – 1 piece
b)
Sample Plate – 1 piece
c)
Large Magnifier – 1 piece
d)
Optic Figure Sphere – 1 piece
e)
Power Cord
f)
Universal Plug Adapter
Using the Polariscope
Before you test any stone with the polariscope, clean it with a gem cloth and confirm
that it is transparent to translucent and not assembled. The polariscope is not used
to test opaque or assembled stones.
To test a stone:
1. Place the rotatable sample plate on top of the polarizer.
2. Turn on the polariscope using the ON/OFF switch on the back of the device.
3. While looking through the analyzer with the light source on, note that continuous
rotation of the analyzer causes the field to become alternately light and dark. Turn
the analyzer to the position where the field is darkest (analyzer and polarizer are
in a crossed position).
4. Place the stone on the sample plate.
5. Rotate the sample plate a full 360° and observe the stone’s reaction while
looking through the analyzer. The stone’s reaction will indicate one of the
following results.
Singly Refractive (SR):
If the stone remains dark during rotation, it could be singly
refractive or it could be a doubly refractive stone that is positioned along its optic
axis. In this case, reposition the stone so that it is viewed in a second and then a third
direction. If the stone remains dark in three positions, it is singly refractive.
Doubly Refractive (DR) or Anomalous Double Refraction (ADR):
If the stone
alternates from dark to light every 90° (see figure 1), it indicates that the stone is
doubly refractive or it is a singly refractive stone that shows anomalous double
refraction. To confirm that the stone is doubly refractive, rotate the stone to its
lightest position and then turn the analyzer from dark to light position. If the stone
remains the same or appears darker as you turn the analyzer, it is doubly refractive.
If the stone gets lighter as you turn the analyzer, it is singly refractive with internal
strain showing anomalous double refraction.
Aggregate (AGG):
If the stone remains light during rotation, it is an aggregate.
Note that highly included stones can give a false AGG reaction. Consider only the
transparent areas of the stone.
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b
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d
e
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