Grading & Branding | Stress Scope

Why To Use a Stress Scope?

What Does A Stress Scope Contain?

Stress Scope is a kind of Polarizing microscope, which is ordinary transmitted light microscope in which polarizing plates are set above and below the specimen. In the usual mode of operation these plates or polars are set with their optic axes mutually perpendicular, so that no light can traverse both plates, and the field of view in the microscope is quite dark.
It is well known that certain transparent crystals exhibit birefringence or double refraction, a phenomenon which causes a beam of light entering a crystal to be split into two separate beams of different polarization.
The presence of an inclusion in any crystal produces a certain amount of elastic strain or distortion in the surrounding lattice, and in some crystals including diamond, these strains cause the crystal to become birefringent. Hence the crystal viewed between polars is seen to pass light through the regions of strain, the light being more intense the greater the strain.
Using a white source of light, the transmitted light is white at low levels of birefringence, but with greater strains shows a spectrum of characteristics colours.

Types Of Stress

Stress can be mainly classified in two categories :

LOCALIZED STRESS:

Localized Stress can be located in any part of the diamond, and is localized. While working with the diamond, if plane of operation passes through this localized stress point, the stone is likely to result in damage.

LEOPARD SKIN STRESS:

Leopard Skin Stress can be generally found spread in the diamond. These stones are highly sensitive to temperature gradient. If the stone is heated and suddenly cooled during any of the process, the diamond is likely to damage. Such stone can easily explode if no proper care is taken at the time of manufacturing.

How To Use A Stress Scope ?

Adjust the Top and Bottom polar axes mutually perpendicular, so that no light can traverse both plates, and the field of view under the magnifying lens is quite dark. Then hold the diamond using tweezers; placing it in between the two optics, and try to see from the top optics, through magnifying lens.