Glass is a wonder material with different interesting properties with a diverse range of applications in our day-to-day lives. It is equally important in our commercial lives too. Under various classifications of glasses "optical glass" forms a very significant part due to its exclusive property of transparency to different wavelengths of light, again for the most important application for our vision as "eye glasses". Coloured glasses form an important sub-class of optical glasses, as they can be used to protect our eyes from undesirable wavelengths of sunlight, and also our buildings from excessive sunlight. Coloured glass, or rather how colouration occurs in glasses forms a vast area of research on "optics". The theoretical aspect of coloured glass is dealt with in Part 1 of this paper.
