The RDI Is the average of the 25 highest categories on the Rapaport price list (D IF – H VS2)

RDI usually references 1ct, but you can calculate RDI for every size

Unlike the RAPI, this is not published regularly.

The RapNet Diamond Index (RAPI) is the average of the cheapest/best-priced 10 diamonds for Round, D-H, IF-VS2, GIA Graded, Rapaport Specification 2 or better diamonds offered for sale on RapNet. ie: The top 25 highest categories (RDI)

While the RAPI indices are available for 0.30 Ct, 0.50 Ct, 0.70 Ct, 1.00 Ct,2.00 Ct, and 3.00 carat size categories, the primary index is one carat size.

The RAPI is published daily in TradeWire and on the RapNet home page.