Identifying Gems and Minerals: A Comprehensive Polariscope Testing Guide

Testing of Gems Mineral for Identification through Polariscope

Polariscope is used for minerals and gem identification to check the authenticity and to determine the actual worth of the gems. Many varieties of rocks, gems, and minerals around the world have distinct properties. Gems and minerals are tested through different instruments and tools to assess them. The instruments are used to validate the observations collected through the eye. The information gathered through the instrument is collected, analyzed, and tested to gauge the real value of minerals and gems. Testing of minerals and gems is used to avoid scams about the fakeness or synthetic produced stones. 

What is Polariscope?

The most common instrument is a polariscope to check and test the gems and minerals. A polariscope is an instrument used for checking gems and minerals in gemology. There are three types of methods that are widely used to test gems and minerals. It includes single refraction, double refraction, and poly-crystalline material or anomalously double Refractive (ADR). Testing of gems and minerals through observation is enough that is why specific methods are used to identify gems. The gems and minerals had to go through different methods to determine the real worth of gems. It is checked using different techniques that require attention on the part of the observer who is using the polariscope to test stones and minerals.

The name of the device suggests that minerals and gems are observed through different angles or points by experts in gemology. A polariscope helps in gathering information about gemstones by observing different lights emitted by gems in the process. A polariscope is an optical device to see and check different physical and chemical prosperities of minerals and gems. Polariscope depends on the light source that is passed through the two Polaroid lenses. The certification of gemstones is given after observing under the polarized lenses of a polariscope to determine the type of gemstones whether they fall into the category of synthetic natural or glass gemstones. 

A polariscope consists of two lenses. The lens on the top of the polariscope is commonly known as the analyzer. The gemstones are observed through an analyzer lens for initial examination. There is another lens located at the bottom of the polariscope called a polarizer that checks the refraction of light from the gemstones. There is a tint plate on the bottom polarizer lens of the polariscope that is used to rotate the gemstones at all angles within 360 degrees. The gemstones are rotated around 360 degrees to check all sides of gemstones to examine all their physical properties. A polariscope is a useful instrument for observing different types of gemstones and certification is given after careful observation of gemstones. 

How to Analyze Gems Mineral through Polariscope?

There is a phase process that is used by Polariscope to test gemstones. 

Ist Phase Test

Step 1:

The first step consists of three stages. The gemstones are rotated under the analyzer lens to see whether it is completely dark or has some light on its own. 

Step 2: 

In the second step, gemstones are placed under the polarized lens. In this step, additional checks are being made to observe the emitted light from the gemstones.

Step 3:

In step three gemstones are moved around the Tint plate at 360 degrees to record the refraction of light from the gems.

2nd Phase of Test for Further Confirmation:

Step: 1

The gemstones are rotated to assess and examine any light emitted from them. The gemstones appear dark when no light is reflected from them.

Step: 2 

The step two gemstones are placed on a polarizer lens to further test other qualities.

Step: 3 

In step three gemstones are observed in full light to check other characteristics.

Step: 4 

In step four gemstones are moved around the analyzer lens to examine the final state of the gemstone. 

Type of Identifications of Gems Mineral through Polariscope

These are some of the outcomes of tests used for the identification of gems and minerals.

1. SR ( Single Refraction) / isotropic / Cubic crystalline
2. DR (Double Refraction) Anisotropic
3. ADR (Anomalously double refractive)
4. Anisotropic Aggregate (Polycrystalline)

1- SR (Single Refraction) / isotropic / Cubic crystalline

Observations:

The gemstone is dark while rotated around 360

degrees on the Tint plate. The single refractive of isotropic gemstones has a consistent dark light. In the second test, when gemstones emit bright light that is called single refraction which occurs commonly in crystalline gemstones. 

Conclusions

The bright light emitted from gemstones is due to the single refraction. 

The isotropic gemstones are amorphous or cubic.

Examples

Garnet, spinels, paste, natural glass, fluorite, diamond, opal and plastics

2- DR (Double Refraction) Anisotropic

The single ray of light that goes into anisotropic divides the single ray of light into two rays of light. It is also known as double refraction.

Observations 

The gemstones turned light and dark four times during the 360-degree rotation in the polariscope. In the case of the double refractive, gemstones formulate different light patterns. In some cases, gemstones may appear dark and light both at the same time. It usually occurs in crystalline gemstones.

Conclusions

The anisotropic gemstones are one axis (uniaxial) or two axes (biaxial). They may have one angle or two angles in their structure.

Examples

Beryl, Chrysoberyl, Corundum, feldspar, peridot, quartz, topaz, tourmaline, zircon, tanzanite

3-ADR (anomalously double Refractive)

In anomalously double refractive gemstones change from dark to light at all 90°. The gemstones are only one-time refractive. The stones are refractive one time but appear to be anomalous double refractions. This unique phenomenon occurs in some gemstones.

Observations: 

Gemstones have an anomalous effect. In anomalous effect, gemstones have double refraction. The gemstones make bands of dark and light refraction. The uniform refraction of light occurs in glass and synthetic stones.

Conclusions

The strain anisotropy is formed occurs usually in isotropic material.

Examples

Almandine, garnet, diamond, paste, natural glass, Verneuil, synthetic spinel, some plastic, amber, and some fire opals.

4-Anisotropic Aggregate (Polycrystalline)

The similar charges among the particles

in an anisotropic fluid that is formed in the nematic liquid crystal phase lead to the formation of aggregate morphologies. The anisotropic aggregate is different from what is formed in isotropic fluids.

Observations:

In this case, the gemstone gives only bright light. Stone stays light through 360-degree rotation in all orientations.

Conclusions

Some twin crystals and triplets and Polycrystalline are anisotropic aggregates.

Examples

Jadite, Nephrite, Chalcedony, Agate, Twinned sapphire, sapphire, and synthetic ruby.