Diamond Price Trends 2026: Which Shapes and Sizes Are Rising or Falling?

Last Updated: June 29, 2026 | Reading Time: 16 minutes

Diamond Price Trends 2026: Which Shapes and Sizes Are Rising or Falling?

The 2026 diamond market is not moving in one direction. Under the surface of "prices flat YTD" - the headline you'll see in trade press - there are shapes appreciating 3-4% and shapes falling 7%. Sizes gaining and sizes losing. The bifurcation is the story. This trend report identifies the specific shape × carat cohorts driving H1 performance, explains the underlying supply and demand mechanics, and lays out our AI-assisted forecast for H2 2026 and Q1 2027.

Winners: What's Rising in 2026

Six shape × carat × quality cohorts have appreciated meaningfully in the first half of 2026. Every winner shares one of two structural drivers: supply constraint (rough diamond scarcity, mine closures) or demand tailwind (fashion cycles, celebrity influence, cultural shifts).

Cohort	YTD Change	Jun 2026 Median	Primary Driver
3ct+ D-F VVS Round	+4.7%	$132,500	Argyle closure; De Beers production cuts
3ct Emerald F VVS2	+2.1%	$44,800	Meghan Markle effect on step cuts
2ct Oval G VS2	+3.1%	$16,850	Sustained celebrity engagement demand
1.5ct Elongated Cushion	+2.4%	$8,720	TikTok-driven antique revival
2ct Round F VS1	+1.1%	$24,800	Rough supply constraint at 4-6ct rough
1ct Oval G VS2	+1.4%	$3,980	Oval market-share gain (17% → 24% since 2020)

Deep Dive: Why Ovals Are Winning

Oval is the standout story of H1 2026. It's the only shape in positive YTD territory across all major carat sizes. Search demand (Google Trends) for "oval engagement ring" has tripled since 2020 while "round engagement ring" has been flat. Celebrity engagement tracking shows 41% of high-profile 2024-2026 proposals featured oval center stones - up from 12% in 2020. The elongated silhouette makes the diamond appear 10-15% larger than an equivalent-carat round, a value proposition that resonates in a cost-conscious market. Oval's historical discount to round has compressed from 25% (2020) to 18% (June 2026) - see the full analysis in Diamond Price by Shape 2026.

Deep Dive: Why 3ct+ Is Recovering

Two supply shocks are still metabolizing. The Argyle mine in Australia closed in November 2020 and had been responsible for roughly 90% of world pink diamond supply plus a meaningful share of small-to-mid rough. De Beers cut production by an additional 22% in 2024-2025 to defend prices in a soft market. The delayed effect on 4-6ct rough (which yields 2-3ct polished) is now showing up: median 3ct+ prices have appreciated in five of the last six months, and dealer inventory reports show 3ct+ carrying costs at their tightest since 2019.

Losers: What's Falling in 2026

The losing cohorts share a mirror pattern: lab-grown cannibalization at entry price points, or fashion cycle exit for shapes that peaked years ago.

Cohort	YTD Change	Jun 2026 Median	Primary Driver
1ct Marquise Natural	-6.9%	$3,745	8th straight quarter of decline; out of fashion
0.5ct Round I SI1 Natural	-5.8%	$1,120	Displaced by lab-grown at entry price
1ct Princess Natural	-4.1%	$3,485	Cushion has absorbed princess demand
1ct Heart Natural	-3.7%	$3,580	Niche; declining anniversary-band demand
All Lab-Grown 1ct	-14.2%	$1,060	Production cost compression
0.75ct Round G-H SI1 Natural	-3.6%	$2,410	Weak, shrinking demographic cohort

Deep Dive: Why Marquise Keeps Falling

Marquise has now declined in 8 consecutive quarters - the longest losing streak of any shape in our dataset. The shape peaked in the late 1980s (Vanna White's 6-carat marquise engagement ring was the cultural moment), and it has been slowly losing share since 2010. Modern buyers gravitate toward softer, more organic silhouettes (oval, elongated cushion) - the sharp points of a marquise now read as dated to many buyers. Retailers have responded by carrying less marquise inventory, which reduces marketing visibility and reinforces the decline. This is not a cyclical dip; it's a structural fashion exit.

Shape Trend Comparison (YTD 2026, 1ct G VS2 EX Natural)

Shape	YTD Change	12-mo Change	Market-share Change (5-yr)	Trend
Oval	+1.4%	-1.1%	+7 pts	🔼 Rising
Emerald	-0.8%	-2.2%	+3 pts	➡️ Stable
Cushion	-1.6%	-3.4%	+4 pts	➡️ Stable
Pear	-1.9%	-3.6%	+2 pts	➡️ Stable
Round	-2.1%	-4.8%	-9 pts	🔽 Softening
Radiant	-2.4%	-4.9%	Flat	🔽 Softening
Asscher	-3.2%	-5.1%	-1 pt	🔽 Softening
Heart	-3.7%	-6.8%	-2 pts	🔻 Falling
Princess	-4.1%	-6.9%	-4 pts	🔻 Falling
Marquise	-6.9%	-11.4%	-2 pts	🔻 Falling

Carat Trend Comparison (YTD 2026, Round Natural G VS2 EX)

The clearest pattern in the 2026 dataset: the smaller you go, the softer the market. The larger you go, the stronger.

• 0.50ct: -4.8% YTD. Cannibalized head-on by lab-grown at $250-$400 price point.
• 0.75ct: -3.6% YTD. Same story, slightly less cannibalization exposure.
• 1.00ct: -2.1% YTD. Stabilizing after 22 months of decline. Positive May-June inflection.
• 1.50ct: +0.4% YTD. First positive turn since Q3 2023.
• 2.00ct: +1.1% YTD. Recovering on tight rough supply.
• 3.00ct: +3.1% YTD. Argyle closure metabolizing.
• 4.00ct+: +4.7% YTD. Trophy segment outperforming; supply is inelastic.

This is a textbook barbell market - the ends outperform the middle. Small stones fall; large stones rise. The middle (1-1.5ct) stabilizes. Every historical diamond cycle we've mapped has ended with this pattern, which usually precedes a broader recovery by 2-4 quarters. See the underlying data in our Diamond Price Index 2026 report.

Supply & Demand Fundamentals

Supply Side

• Rough production: Global rough diamond production is projected at 108M carats in 2026 - down from 141M in 2019 (pre-COVID). Structural decline of 4-6% annually since 2019.
• Argyle closure impact: The Argyle mine (Australia) closed November 2020. It had produced ~14M carats annually, ~10% of global supply. Impact on small stone supply metabolized 2021-2023; impact on larger stones (4-6ct rough → 2-3ct polished) now showing up in 2026 prices.
• De Beers production cuts: De Beers reduced 2024-2025 production by 22% to defend prices during the demand slump. Restraint continues in 2026.
• Lab-grown production: Grew 34% year-over-year in 2025. Cost per carat continues to decline as CVD reactor scale improves and Chinese HPHT capacity comes online.

Demand Side

• US engagement volume: ~1.9M US engagements projected in 2026, roughly flat vs 2025.
• Lab-grown share of engagement center stones: 52% in 2026 (up from 12% in 2020, 41% in 2024).
• Chinese demand: Recovering slowly; still 30% below 2019 peak.
• Indian demand: Rising steadily on wedding-market growth; +6% YoY in 2025-2026.
• Investment demand: Small but growing - colored diamond auction results at all-time highs; white diamond investment demand still niche.

Quality-Tier Movement

Within the round 1ct universe, the color and clarity tiers are moving differently. Higher tiers are holding; lower tiers are softer.

Quality Tier	Median (Jun 2026)	YTD	12-mo
D-F, IF-VVS (Top)	$9,850	+0.3%	-1.4%
G-H, VS (Mid - Benchmark)	$4,850	-2.1%	-4.8%
I-J, SI (Entry)	$2,780	-4.9%	-8.7%

Top-tier quality (D-F IF-VVS) is stable - investment-grade natural diamonds are a distinct market segment less exposed to lab-grown competition and increasingly viewed as a store of value. Mid-tier is the benchmark. Entry tier faces the hardest competitive pressure from lab-grown, which delivers equivalent visual quality for 75% less.

AI Outlook: H2 2026 & Q1 2027 Forecast

Our forecast combines three model families: (1) time-series decomposition of the 6-year price history, (2) demand-side modeling from Google Trends, retailer inventory turn, and macro consumer-confidence data, and (3) supply-side modeling from mine production forecasts and lab-grown reactor capacity growth. Ranges below reflect the middle 60% of Monte Carlo simulation outputs.

Segment	Q3 2026 Range	Q4 2026 Range	Q1 2027 Range
1ct Round Natural G VS2	$4,720 – $4,880	$4,700 – $4,900	$4,750 – $4,950
2ct Round Natural F VS1	$24,900 – $25,600	$25,300 – $26,400	$25,800 – $27,200
3ct Round Natural F VVS2	$69,500 – $72,000	$71,000 – $75,000	$73,000 – $78,000
1ct Round Lab-Grown G VS2	$950 – $1,020	$860 – $940	$780 – $880
1ct Oval Natural G VS2	$4,020 – $4,120	$4,080 – $4,220	$4,150 – $4,320

Baseline forecast summary: Natural round 1ct holds the current floor near $4,850 with mild recovery beginning Q4. Larger natural (2ct, 3ct) continues to appreciate. Lab-grown falls another ~18% by Q1 2027. Oval and elongated cushion continue their outperformance.

Buyer Implications: What This Means for You

If you're buying under 1.5ct natural

The trend is your friend - prices in your target segment are stable or falling. No urgency; buy on your timeline. Use the August seasonal window (see Best Time to Buy a Diamond in 2026) to capture an additional 7-9%.

If you're buying 1.5ct+ natural

The trend is against you - larger stones are appreciating and inventory is tightening. If your timeline is flexible over months, don't wait; the segment is more likely to be more expensive in 3-6 months than cheaper. Still capture August seasonal timing.

If you're buying lab-grown

The trend strongly favors waiting. Every 6 months costs you roughly 10-12% of value. If your deadline is elastic, delay until Q1 2027 to capture full trend + seasonal impact (combined ~20% savings vs today).

If you're buying an oval or elongated cushion

You're in the winning cohort. Prices are stable to slightly rising. Don't wait for a discount that isn't coming; buy now if you want the shape.

If you're considering marquise, princess, or heart

You're in the losing cohort. Prices will likely be 3-5% cheaper in 6 months. If you love the shape, use that patience to your advantage. Note: falling prices also mean weaker resale - buy for love-of-object, not investment.

Frequently Asked Questions

Are diamond prices going up in 2026?

Mixed. Natural diamonds 1.5ct and above are appreciating (up 1-5% YTD). Natural diamonds under 1.5ct are declining (down 2-5% YTD). Lab-grown is falling across the board (down 14% YTD at 1ct). See the full Diamond Price Index 2026 for the numbers.

Which diamond shape is rising in value in 2026?

Oval is the only shape in positive YTD territory across all major carat sizes (+1.4% at 1ct, +3.1% at 2ct). Emerald cut is stable. All other shapes are declining, with marquise (-6.9%) and princess (-4.1%) the weakest.

Which diamond size holds value best?

3ct and larger. Rough supply constraint has driven 3.1% appreciation at 3ct and 4.7% at 4ct+ in H1 2026. This is a supply-driven trend expected to persist into 2027 as Argyle closure and De Beers production cuts continue to metabolize.

Will lab-grown diamond prices keep falling?

Yes - our production-cost model implies another 18-25% decline over the next 12 months before lab-grown prices approach marginal cost. Expected 1ct lab-grown median: $780-$880 by Q1 2027, versus $1,060 today.

Is now a good time to buy a diamond?

Yes, for most segments. Natural under 1.5ct is at or near the multi-year floor. Natural 1.5ct+ is beginning to recover - waiting risks paying more. Lab-grown is the one segment where waiting is clearly rewarded. See Best Time to Buy a Diamond in 2026 for the full timing framework, including the August seasonal window.

What's the safest shape choice for resale value?

Round (still - despite the -2.1% YTD move, round retains the deepest secondary market) or oval (if you value fashion tailwind). Avoid marquise, heart, and asscher if resale matters - thin secondary markets and declining demand.

Bottom Line: The 2026 Diamond Trend Playbook

The 2026 diamond market has decoupled into three clear tiers: large + high-quality natural (rising, supply-driven), mid-market natural (stabilizing after long decline), and lab-grown + small natural (still falling on cost compression and cannibalization). Match your purchase to the trend: if you're buying large or oval, don't wait. If you're buying small or lab-grown, do wait. Combine the trend with the August seasonal window and 5-retailer comparison shopping for maximum value capture.

Ready to price your specific target? Use the Diamond Price Calculator to see live median pricing against these trends, or browse live retailer inventory for the diamonds behind the numbers.