The IDEX Polished Price Report is a daily, electronically published price grid for polished diamonds, produced by IDEX Online, the Israel Diamond Exchange-affiliated trading platform headquartered in Ramat Gan, Israel. Unlike weekly printed or PDF price sheets, the IDEX index is derived from actual asking prices and completed transactions recorded on the IDEX Online marketplace, and is refreshed continuously throughout the trading day. It covers round brilliant-cut diamonds and a range of fancy shapes across the standard GIA colour scale (D through M and beyond) and clarity grades from Flawless to I3, making it a comprehensive reference across the commercial spectrum of polished goods. Within the diamond trade, the IDEX Polished Price Report is regarded as the principal alternative to the Rapaport Diamond Report, and its methodology — anchored in live platform data rather than editorially set benchmarks — gives it a distinct character as a market-liquidity indicator.

Background and Publisher

IDEX Online was established in the late 1990s as an electronic marketplace designed to bring greater efficiency and transparency to the international polished-diamond trade. It operates under the auspices of the Israel Diamond Exchange, one of the world's largest and most influential bourses, and draws its membership from dealers, manufacturers, and wholesalers across the major diamond centres — Antwerp, Mumbai, New York, Hong Kong, and Tel Aviv. The platform functions as both a trading venue and a data-aggregation service; because every listing and transaction is logged, the accumulated pricing data forms the empirical basis for the Polished Price Report. This architecture distinguishes IDEX from price-reporting services that rely on surveyed opinions or editorially adjusted benchmarks.

Methodology and Data Sources

The IDEX index is constructed from the asking prices posted by sellers on the platform, weighted and adjusted to reflect actual transaction levels where those data are available. Prices are expressed as US dollar figures per carat for each cell in the grid, with cells defined by the intersection of shape, weight range, colour grade, and clarity grade. The most liquid cells — such as round brilliants in the 1.00 ct range graded G/VS2 or H/SI1 — are updated most frequently and carry the greatest statistical confidence; thinner markets, such as large fancy-colour goods, are represented with less granularity.

Because the underlying data are drawn from a live marketplace rather than from a weekly editorial process, the IDEX index can reflect intraday price movements during periods of rapid market change — a quality that became particularly visible during the volatility of 2020–2022, when supply-chain disruptions and shifting consumer demand caused polished prices to move sharply within short windows. This responsiveness is both the index's principal strength and a source of occasional criticism: in illiquid size-colour-clarity combinations, a small number of listings can produce price readings that diverge meaningfully from broader market consensus.

Coverage: Shapes, Sizes, and Grades

The report covers the following categories:

• Round brilliants from 0.01 ct melee through 10.99 ct and beyond, segmented into standard sieve and carat-weight brackets.
• Fancy shapes including princess, oval, pear, marquise, emerald cut, cushion, radiant, and heart, though coverage depth varies by shape and size.
• Colour grades D through K (and selected lower grades for commercial melee).
• Clarity grades FL/IF through I3, with combined cells at the extremes of the scale where market depth is limited.

Fancy-colour diamonds — natural yellows, pinks, blues, and other hues — are not comprehensively covered by the standard IDEX grid, reflecting the bespoke, auction-driven nature of that market segment, where no standardised price grid has achieved broad acceptance.

Comparison with the Rapaport Diamond Report

The Rapaport Diamond Report, published weekly by Rapaport Group since 1978, has historically been the dominant pricing reference in the polished-diamond trade. Rapaport prices are set editorially and represent high asking prices for top-quality goods in each category; actual transaction prices are conventionally quoted as a percentage discount to the Rap sheet (e.g., "minus 30" for a stone trading at 30 per cent below list). This convention is deeply embedded in trade practice, particularly in the United States and among GIA-certified goods.

The IDEX Polished Price Report positions itself differently: its prices are intended to reflect where goods are actually trading, not an aspirational ceiling. Proponents argue that IDEX prices therefore require less interpretive adjustment and offer a more transparent signal of real-time liquidity. Critics note that because IDEX prices are derived from a single platform's listings, they may not capture the full breadth of off-platform transactions, particularly for large or unusual stones that are traded privately. In practice, many dealers consult both reports, using Rapaport as a structural reference and IDEX as a real-time market check.

Use in the Trade and Investment Context

The IDEX Polished Price Report is used by a broad constituency within the diamond pipeline:

• Manufacturers and wholesalers use it to price outgoing stock competitively and to assess the relative value of rough-to-polished conversion at current market levels.
• Retailers reference it when negotiating with suppliers, particularly for certified round brilliants where the grid is most liquid.
• Investors and funds considering diamond-backed instruments have cited IDEX data as a mark-to-market reference, though the absence of a universally accepted polished-diamond index remains a structural challenge for the asset class.
• Gemmological laboratories and appraisers may consult IDEX data as one input in replacement-value or fair-market-value assessments, alongside auction results and dealer quotations.

It is important to note that no polished-diamond price index — IDEX or otherwise — constitutes a guarantee of liquidity. The diamond market remains fragmented, relationship-driven, and sensitive to certification provenance (stones graded by GIA or AGS typically command premiums over equivalently graded stones from less-recognised laboratories). An IDEX price reading for a given grade combination represents a market average or midpoint, not a firm bid for any specific stone.

The IDEX Polished Diamond Index

In addition to the detailed grid, IDEX publishes an aggregate IDEX Polished Diamond Index — a single composite figure that tracks the weighted average price movement of polished diamonds across the platform. This index is updated daily and is used by market observers as a headline indicator of overall polished-diamond price trends, analogous in function (though not in methodology) to a commodity spot index. The index gained wider attention during the post-pandemic period when polished prices rose sharply through 2021 and then corrected through 2023, providing a publicly accessible record of those movements.

Limitations and Caveats

Several limitations should be kept in mind when interpreting IDEX data:

• Prices reflect asking levels on a single platform; off-market and auction transactions are not captured.
• Thin cells (unusual sizes, low-demand colour-clarity combinations) may be statistically unreliable.
• The index does not account for stone-specific quality factors — cut quality, fluorescence, polish, symmetry — that can cause individual stones to trade at significant premiums or discounts to grid levels.
• Currency fluctuations affect the US dollar price grid's relevance for buyers operating in other currencies.
• The index covers only natural polished diamonds; laboratory-grown diamonds, which have experienced dramatic price declines since 2020, are tracked separately and are not reflected in the standard Polished Price Report.

Further Reading

• GIA Gems & Gemology — Diamond Price Reporting in the Modern Trade
• IDEX Online — Polished Diamond Prices