The finest and most valuable diamonds are absolutely colorless. Sometimes what you want to look for depends on the type of jewelry. Here are buying jewelry quality marking general guidelines.
Diamond Certificate
Explanation of Cut, Color and Clarity of This Diamond
Cut Quality The ideal cut diamond is a very precise mathematical equation, where diamond proportions and angles are cut to optimize the diamond's superlative optical properties, in particular it's high refractive index and color dispersion, to create a diamond of unequaled beauty with perfect balance of brilliance and fire. In layman's terms, the diamond is cut to make it the most beautiful diamond so it retains its intrinsic value.
Color When mounted, G color grade diamonds will appear colorless except to the trained eye. G color may be noticeable when compared to diamonds of better grades. Diamonds of G color grade offer excellent value. For an excellent value in a diamond with no noticeable color to the unaided eye, G color diamond is the right choice.
Clarity SI1 clarity diamonds are slightly included. SI1 diamonds have some inclusions visible under 10x magnification but not easily visible to the naked eye. A diamond with this grade of clarity is an excellent choice for someone on a limited budget.