OpenFacet – Diamond Composite Index (DCX)
Benchmark Specs (Round, 3EX, Non-Fluorescent) - Weight-Adjusted Price & Liquidity View Reference Price per Carat by Spec (Round, 3EX, Non-Fluorescent)
DCX history
Historical nominal DCX in USD per carat, alongside a DXY/gold-adjusted comparison rebased to the selected period.
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| Spec | $ / ct | Change % | Weight | Weighted Value |
|---|
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Clear, structured data for pricing context:
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- Reference price lists by spec
- Market shift observations and notes
Online retail scarcity
Each round-diamond specification is ranked against 960 combinations modeled from the online retailers we cover. A rank of 90 indicates lower estimated availability than approximately 90% of them.
Scarcity across carat sizes
Median scarcity rank and 10th–90th percentile range across 80 color/clarity combinations at each carat size.
The shaded range shows variation across specifications, not model uncertainty.
How scarcity varies by grade
At each carat size, compare median scarcity rank by color or clarity; ranks use a fixed 0–100 scale.
These are relative ranks, not absolute market supply. Each bar is the median across the other grade axis.
How the availability sweet spot shifts with size
At each carat band, the point is the actual color/clarity combination nearest the center of its 20 lowest-scarcity specifications (the medoid).
Positions compare relative availability within each carat band, not absolute supply. Lines connect published sizes only.
Where specifications enter the scarcest quarter
Earliest carat band from which each color/clarity combination remains in the scarcest 25% at every published size through 6 ct.
Thresholds apply only to published carat sizes through 6 ct, not intermediate sizes or larger stones.
Individual specifications
Select a carat size to compare scarcity ranks across color and clarity grades.
Understanding scarcity ranks
| Score | Market availability |
|---|---|
| 0–<20 | Widely Available |
| 20–<40 | Moderately Available |
| 40–<60 | Limited Availability |
| 60–<80 | Rare |
| 80–100 | Very Rare |
Classifications describe relative online retail scarcity, not guaranteed inventory availability.
The OpenFacet Diamond Composite Index (DCX) is a transparent benchmark that tracks per-carat retail prices for natural GIA-certified round diamonds with 3EX grading (cut, polish, symmetry) and no fluorescence. It focuses on high-liquidity segments, smoothing per-carat price data across color and clarity grades within fixed carat bands.
DCX serves as a diamond price index, derived from structured retail inventory snapshots and processed using log-linear and geometric interpolation techniques. This ensures consistency, interpretability, and responsiveness to market dynamics, while filtering out anomalies and unavailable specs. The DCX is updated regularly and is designed for integration into diamond pricing engines, retail quoting tools, and market analysis dashboards.
DCX supports valuation workflows, algorithmic pricing, market tracking, and synthetic asset modeling. For full methodology and construction details, see the About OpenFacet & DCX Methodology page.
Disclaimer: The Diamond Composite Index (DCX) is a model-based benchmark constructed from public retail listings. It does not represent executable prices or financial advice. All data is filtered, interpolated, and smoothed for index use. Use at your own discretion. GIA is a registered trademark of the Gemological Institute of America. This site is not affiliated with, endorsed by, or associated with GIA.