Diamond Price Per Carat Index — 2026
A live, dated 2026 index of retail per-carat ranges for natural and lab-grown diamonds — by shape family, carat weight, and major grading lab (GIA, AGS, IGI). Trade-desk directional bands, not a Rapaport reprint.
How to read this index
Every row is a per-carat rate, not a total. Multiply by the actual carat weight to get the total price. Bands cover G–J color, VS–SI clarity, strong cut, on a major-lab report. D–F / VVS goods sit above the top of each band; J / SI2 sit at or below the bottom. Fluorescence, exact proportions, and lab choice can push an individual stone outside the band in either direction.
Round brilliant is the reference shape. Fancy shapes (oval, emerald, pear, cushion, radiant, marquise) typically run 15–30% cheaper per carat at the same spec because they retain more weight from the rough. Lab-grown is on a separate, far flatter curve — the natural-only "magic weight" premium at 1.00 / 1.50 / 2.00 ct is muted on lab-grown because there is no rough-rarity scarcity.
Natural vs. lab-grown — round brilliant and fancy shapes
Read across, then multiply by carat weight. Natural columns assume GIA or AGS; lab-grown columns assume IGI or GIA. A stone without a major-lab report does not belong on this chart at any price.
| Carat weight | Natural round GIA / AGS · per ct | Natural fancy GIA / AGS · per ct | Lab round IGI / GIA · per ct | Lab fancy IGI / GIA · per ct |
|---|---|---|---|---|
| 0.50 ct | $2,000–$4,500 | $1,600–$3,600 | $250–$500 | $200–$400 |
| 0.90–0.99 ct | $4,000–$7,500 | $3,200–$6,000 | $350–$700 | $280–$560 |
| 1.00 ct | $5,500–$9,500 | $4,400–$7,500 | $450–$900 | $360–$720 |
| 1.50 ct | $7,500–$13,000 | $6,000–$10,500 | $550–$1,100 | $440–$880 |
| 2.00 ct | $11,000–$18,000 | $8,500–$14,500 | $700–$1,400 | $560–$1,120 |
| 3.00 ct | $17,000–$30,000+ | $13,000–$24,000 | $900–$1,800 | $720–$1,440 |
Where the threshold jumps land
On natural goods, the per-carat rate steps up at 1.00 ct, 1.50 ct, and 2.00 ct. The 2.00 ct mark is the steepest in percentage terms — a 1.90 ct stone can sit 30–50% under a 2.00 ct twin in per-carat rate, layered on top of the weight difference. A 0.95–0.99 ct round faces the eye as a one-carat and saves 15–25% per carat versus a true 1.00 ct of identical spec.
On lab-grown, these dips are mostly cosmetic. There is no rough-rarity reason for a 2 ct lab stone to cost categorically more per carat than a 1 ct lab stone, and the market has priced that in. Shopping just-under-threshold on lab-grown is not the leverage move it is on natural.
What this index is — and what it is not
Bands are derived from trade-desk visibility into wholesale benchmarks (Rapaport list is quoted off and discounted from at the wholesale tier — typically 20–40% below list), the IDEX Online Polished Diamond Price Index for directional movement, and public auction comparables for the top of the natural curve. We do not reproduce the Rapaport sheet, and we do not publish single-point prices for specific specs because diamond pricing is a range business and any precise figure for "a 1 ct G VS1" is selling, not informing.
Lab-grown bands reflect the continuing year-over-year price compression in the segment. A lab stone purchased at the top of its band in 2026 will, on current trajectory, be worth less than the bottom of the same band in 2028. If a stable store of value matters, this is not your buy.
Use this index alongside
- The full diamond price per carat 2026 guide — the narrative behind these bands, with the threshold-jump math worked out.
- Lab-grown price per carat by clarity — how the lab-grown curve moves across VS, VVS, and flawless.
- How to negotiate a diamond price — converting these bands into a counter at the desk.
- Lab-grown vs. natural — the economics — why the two columns above sit an order of magnitude apart.
- How to read a GIA diamond report — what the report has to say before the price band applies to your stone.
Methodology and refresh cadence
This index is refreshed on a rolling basis as wholesale benchmarks move and as our trade-desk visibility on completed deals updates. The "last updated" stamp at the top of the page reflects the most recent band review. Bands move in increments — a 5–10% shift in either direction within a quarter is normal; a full reshuffle is not.
If you spot a band that no longer matches what your jeweler is quoting in either direction, that is useful signal. Email the desk and we will pressure-test it against our sources before the next refresh.