Our stores use diamond and gold testers to determine the authenticity of each piece of jewelry we evaluate. We also weigh your jewelry to be sure of its precious metals value. Each piece of jewelry must pass a test verifying the validity of its mark. The electronic test is preferred because it is nondestructive. Once we determine the precious metals fineness, the value is determined based on the current day metals pricing as listed through KITCO.com precious metals market values. All diamonds and precious stones are measured for approximate weight and valued through the appropriate comparable cut/color/clarity & carat (4 C's) as listed in various wholesale websites.