The
color represents the yellow tone a diamond can have, where
D is a perfectly colorless diamond, and
H (the minimum marketed by Valmand) can have slight yellow tones.
Clarity refers to the number and magnitude of the smallest imperfections found in almost all diamonds.
IF is a perfectly clean diamond, and
SI2 (the minimum marketed by Valmand) can have slight visible imperfections under the magnifying glass.
All of these are detailed
here
Valmand suggest diamonds with minimum G color and SI1 clarity, offering a very good quality / price ratio.