Page:A treatise on diamonds and precious stones including their history Natural and commercial.djvu/66

 speaking, the degree of polish which a stone is capable of receiving, depends upon its hardness. That of the Diamond, which renders itso difficult to be cut and manufactured, enables it to retain unimpaired the lustre which it has originally received.

particles, laid on a new anvil and struck with a hammer, will indent both, and in some. cases will not be broken. Yet with this intensity of hardness the Diamond is far from being: difficult of fracture: a slight blow often causes it to split, and the fine edge of a brilliant is frequently injured by clumsy workmen. I have, known one to be chipped by falling on a boarded floor.

formed Diamond, iflightly struck in the direction of the laminæ, will split easily; indeed it admits of cleavage in fourdirections, and I possess a perfect octahedron formed by cleavage. Spheroidal Diamonds break with