H The colour H is part of the colourless group, and indicates a white diamond with no signs of colour visible from either the top or side. SI Clarity is an indication of a diamond's purity. It describes the degree to which a diamond is free of imperfections. The internal clarity grade SI is an indication of high quality, the diamond having only tiny inclusions which are not visible to the naked eye. H/SI indicates specially selected diamonds, hand picked for their whiteness and freedom of inclusions. These are diamonds that you will treasure for their beauty and quality.