RockShop also explains the 4Cs(carat weight, clarity, color, and cut), and helps you understand how each of the grades affects price. A separate calculator is provided for grading cut quality based on GIA lab reports. A database of close to 10,000 diamonds were used to create the pricing model. While the prices are just estimates, over 98% of the pricing variability is explained by the sophisticated multivariate pricing model used by RockShop. The estimated prices are in US dollars, and generally apply to loose round diamonds <= 2 carats in size.