Emerald Fashion Earrings Jewellery collection 17

Emerald Fashion Earrings Jewellery.
By Samina

When even the most practised eye may find it difficult to distinguish between stone of difficult species but of very similar colour, simple instruments can sometimes be used to 'analyes' the colour in one way or another and make the separation simple. what we call 'white' light, i.e. light from the sun or other incandescent bodies, is composed of a mixture of all the colours of the rainbow. newton, in the year of the great fire of london (1666), was the first to show that sunlight has a composite nature. he analysed a narrow beam of light that passed through a 
chink in the shutter into his darkened room, by the simple expedient of placing a glass prism in the path of the ray. light is variously refracted by a transparent solid according to its wavelenght, the red rays, of longer wavelength, beings less deviated than the shorter, violet, waves.There is a point here which may usefully cleared up since it causes confusion to students. what is known as the critical angle of a stone is the angle at which rays of light passing from the stone into air are refracted at 90 to a line prependicular to the surface between the two media . rays striking the inside surface of a stone at angle creater than this critical angle 

cannot emerge, and are totally reflected back into the stone. here the stone is the denser medium, and the higher the refractive index of the stone is the smaller is its critical angle. in the case of refractomemter the principle is exactly the same, but here the glass of the refractometer is the denser medium, and the stone is the rarer medium. thus, in this case the higher the refractive index of the stone the greater is the critical angle between it an the glass of the instrument.