iQu Gem Mart : July 2019

Tuesday, July 9, 2019

what is Polariscope ?

WHAT IS POLARISCOPE ?

Polariscope is an instrument used in gemmology which helps to find if the gemstone is single refractive or double refractive and also allows determining the various crystal axis of the stone. ... A polariscope is made of two Polaroid plates that rotate, a power switch, a stone holder and a bottom light source.

1-
DR is Anisotropic = double refraction means (DR)
SR is Isotropic = single refractive =single colour mean (SR)
2-
7 out of 6 CRYSTALLINE is DR
CRYSTALLINE Cubic System are SR

Pollycrystalline Or Microcrystalline Gemstones do not blink and stay light during 360 degree

3-

POLLYCRYSTALLINE GEMS Stone stays Light through 360 rotaion in all orientaions.

Thursday, July 4, 2019

Advantages

To Gemology
GEMOLOGIST can Identify cleavage in rough and even cut stone hence in helps in the identification of the stone

To Lapidary

CLEAVAGE is Quicker than sawing hardness direction can be find in DIAMOND
due to cleavage
CONCHOIDAL FRACTURE
Citrin Quartz

How Can A tell Cleavage from A Freacture

Cleavage and fracture. When crystals break, they can either split leaving a clean, flat face called a cleavage plane, or fracture leaving a more rough, uneven surface. We can find out more about a crystal by looking at the way it breaks. Cleavageplanes form along the weakest area of mineral's structure

Can a mineral have a cleavage and fracture?

Cleavage and fracture differ in that cleavage is the break of a crystal face where a new face (resulting in a smooth plane) is formed, whereas fracture is the "chipping" shape of a mineral. All minerals exhibit a fracture, even those that exhibitcleavage

Cleavage & Fracture

CLEAVAGE & FRACTURE

Cleavage is the tendency of a mineral to break along smooth planes parallel to zones of weak bonding.

Fracture is the tendency of a mineral to break along curved surfaces without a definite shape. These minerals do not have planes of weakness and break irregularly.