Methodology

CaratRank compares public diamond listings by normalizing retailer data, identifying the certified stone behind each listing, and ranking offers by listed item price.

Data sources

CaratRank uses public or publicly accessible retailer pages, product pages, search results, feeds, APIs, and grading report information. We do not knowingly use confidential retailer data, private inventory systems, stolen credentials, or non-public pricing files.

Matching identical stones

The strongest match is a certificate match. When listings share the same IGI, GIA, or GCAL certificate number, CaratRank treats them as the same certified diamond and compares seller prices directly.

If certificate data is missing, CaratRank may identify likely matches from public listing attributes such as shape, carat, color, clarity, cut, measurements, lab, and seller data. Those matches should be treated as lower confidence than certificate-confirmed matches.

Prices

CaratRank reports listed item price. It does not include tax, shipping, insurance, duties, financing costs, wire discounts, coupons, settings, resizing, warranties, or other charges unless a retailer includes them in the listed item price we observe.

Ranking

Search results rank offers by price by default, with the lowest listed item price first. For the server-rendered price index, summary statistics are calculated from indexed in-stock listings, including low prices, typical prices, stone counts, retailer counts, and last observed update time.

Rankings are based on observed listing data, match confidence, and listed item price. They are not based on retailer payment, referral fees, commissions, paid placement, or other retailer incentives.

Price should not be the only factor in a purchase decision. Shoppers should also consider customer support, return policies, reliability, shipping, warranty handling, and seller reputation. Some retailers may charge a bit more but provide much stronger customer support than others.

Freshness and verification

Retailer inventory changes quickly. A listing can sell, change price, or disappear after CaratRank observes it. CaratRank is a comparison and discovery tool; users should verify certificate, price, availability, taxes, shipping, return policy, and warranty directly with the seller before buying.

Corrections

If a retailer, marketplace, laboratory, or rights holder believes a listing is inaccurate, outdated, non-public, or should not be displayed, they should contact CaratRank with the specific URL, certificate number, field, and reason for review.