What is the AGS cut grade and how is the 0 to 10 scale read?

The AGS cut grade is a continuous numeric verdict on how a round brilliant — and a small set of qualifying fancy shapes — actually performs with light. AGS Laboratories ray-traced the stone, measured brightness, contrast, dispersion, and leakage, and combined those with proportion, polish, and symmetry to print a single number from 0 to 10. 0 is Ideal (the top performance tier and the bucket trade buyers call "AGS 0"), 1 is Excellent, 2 is Very Good, 3 is Good, 4 is Fair, 5 to 9 walk down through Poor performance, and 10 is the bottom of the scale. Lower is better — the opposite direction from the GIA cut scale.

When did AGS Laboratories start using the 0 to 10 cut grade?

AGS Laboratories opened in 1996 and launched the 0–10 scale at the same time, initially as a proportion-based cut grade. In 2005 AGS replaced the proportion model with the AGS Performance Grading Standard — the ray-traced light-performance methodology that became the lab's signature. From 2005 until standalone reports stopped in late 2022 every AGS Platinum Light Performance Diamond Quality Document used the same 0–10 performance scale most buyers think of when they hear "AGS cut grade."

What does an AGS cut grade chart look like in plain English?

Read top to bottom, lowest is best. 0 — Ideal (AGS 0, the top performance bucket; "triple zero" or "AGS 000" means 0 cut + 0 polish + 0 symmetry). 1 — Excellent (a measurable leakage band or contrast asymmetry; visually almost identical to AGS 0 but trades 3–5% lower on naturals above roughly $5,000). 2 — Very Good (roughly the middle of the GIA Excellent proportion band with one or two metrics measurably softer). 3 — Good. 4 — Fair. 5 to 9 — Poor performance, with visible leakage or weak contrast the ASET image will surface. 10 — bottom of the scale. Proportion, polish, and symmetry each get their own 0 to 10 score on the same report.

Did AGS Laboratories close, and is my pre-2022 AGS report still valid?

AGS Laboratories ceased issuing standalone reports in late 2022. The Las Vegas grading facility, the AGS Performance Grading Standard intellectual property, the ray-tracing software, the ASET imaging methodology, and the research staff all transferred to GIA under an acquisition agreement. A pre-2022 AGS Platinum report remains a valid historical document — the grading was real, the stone is the stone, and the report number can still be verified through the agslab.com historical database now archived inside GIA. The non-profit American Gem Society trade association continues to operate separately from the closed lab.

How did GIA absorb the AGS cut-grade methodology?

GIA repackaged the AGS Performance Grading Standard as the AGS Ideal Report, a digital supplement that attaches to an eligible GIA Diamond Grading Report or GIA Laboratory-Grown Diamond Report on qualifying round brilliants and a few fancy shapes. The supplement costs roughly $25 per stone, uses the same ASET light-performance methodology AGS Laboratories used pre-2022, and prints the same 0 grade for stones that meet the standard. The legacy AGS Platinum report and the modern GIA + AGS Ideal supplement are scoring the same physics through the same software — only the paper changed.

How do I read a legacy AGS Platinum Light Performance report?

A pre-2022 AGS Platinum Light Performance Diamond Quality Document has four blocks. The header carries the report number (verifiable at agslab.com), issue date, and stone description. The Performance Grading block prints the headline 0–10 cut grade plus polish and symmetry on the same 0–10 scale. The 4Cs block prints color and clarity on the AGS 0–10 numerics (0.0 = D color, 0 = FL clarity). The back-of-report block shows the ASET image, the proportion diagram, and the light-performance map. Cross-check the laser-inscribed report number on the girdle against the paper and against the agslab.com lookup before money moves.

AGS Cut Grade: Full History of the 0–10 Scale and How to Read a Legacy AGS Report (2026)

A reader emailed last month with a photograph of a 1.32-carat round brilliant her grandmother left her, paper-clipped to a 2014 AGS Laboratories Platinum Light Performance report grading the stone AGS 0/0/0. She wanted to know whether the document was still worth anything now that "AGS closed." It is, and the misunderstanding behind the question is the most common one in the diamond market in 2026: the lab that printed the paper is gone, but the science that printed it is alive, scoring stones every day inside GIA. This guide is the long version of what I wrote back — the AGS cut grade end-to-end, from the 1996 launch of the 0–10 scale through the 2022 closure and into how the methodology now ships as the AGS Ideal supplement on a 2026 GIA report.

It is written for the reader who owns a legacy AGS-graded stone, or who is buying one, or who keeps seeing "AGS 0" in listing copy and wants to know what the number actually verifies. For the head-on AGS-versus-GIA decision on a stone you are buying today, the companion piece is AGS vs GIA: side-by-side grading rubric and the full methodology hub at AGS vs GIA: cut grade and when each matters. For the three-lab decision that adds IGI to the picture, see GIA vs IGI vs AGS.

A short history of AGS Laboratories

The American Gem Society itself is the older institution. Founded in 1934 by Robert M. Shipley — the same Robert Shipley who founded GIA in 1931 — AGS was set up as a trade association of jewelers committed to consumer protection and ethical retailing. For its first six decades AGS did not grade diamonds; it accredited retailers. The grading lab arm came much later.

1996 — AGS Laboratories opens in Las Vegas. Peter Yantzer, formerly of GIA, launched AGS Laboratories as the for-profit grading-lab arm of the AGS trade association. From day one the lab graded everything — color, clarity, cut, polish, symmetry — on a single continuous 0 to 10 numeric scale. The continuous scale was the conscious bet: a number like "AGS 2.5 color" carries finer-grained information than a categorical letter like "GIA G," and the trade can act on the difference. The original cut grade in 1996 was proportion-based, using a measurement model similar in spirit to what GIA would publish nearly a decade later.

2005 — the AGS Performance Grading Standard launches. This is the inflection point. AGS replaced the proportion-based cut model with a ray-traced light-performance model. The lab built a software platform — DiamCalc-based at the engine level, with AGS-proprietary scoring layered on top — that took the actual measured geometry of a stone, ray-traced light through it in three dimensions, and scored four outputs: brightness (the total light returned to the eye), contrast (the dark-light pattern the eye reads as scintillation), dispersion (fire — the rainbow flashes), and leakage (light that escaped through the pavilion instead of returning to the eye). Those four were combined with proportion, polish, and symmetry to print the headline 0–10 cut grade.

The release was paired with ASET — Angular Spectrum Evaluation Tool — a hemisphere device that surrounds the diamond and replaces ordinary light with three coded zones: red for high-angle light (40°–75°, the brightness band), green for low-angle light (0°–40°, the contrast band), and blue for light coming from directly overhead (which a well-cut diamond should obscure as contrast, not return). The ASET image printed on the back of every AGS Platinum report from 2005 onward was a verifiable picture of where the stone was returning light, where it was contrasting, and where it was leaking. For the first time a buyer could see the cut verdict, not just read it.

2006–2010 — extension to fancy shapes. AGS extended the Performance Grading Standard to cushion, princess, emerald, and oval cuts under separate rubrics. GIA never did this for fancies — to this day GIA prints individual measurements for fancy shapes but no overall cut grade. The AGS Performance Grading Standard on a princess or cushion remained the only meaningfully independent light-performance verdict you could attach to a non-round stone, and that gap is still open in 2026.

2010–2022 — adoption plateaus. AGS Laboratories never matched GIA's submission volume. Two structural reasons: the Rapaport list (the trade's dominant per-carat price reference) prices off GIA grades, so GIA paper was always the more liquid resale instrument; and the AGS reports cost more per stone, with the light-performance test adding time and complexity the lower end of the market did not want to pay for. The lab's niche stabilized as the cut-quality specialist — premium rounds where buyers wanted both verdicts, signed-cut branded programs (Hearts on Fire, Whiteflash A CUT ABOVE, A. Jaffe), and "true hearts and arrows" claims that needed an independent verifier.

July 2022 — closure announced. The American Gem Society announced AGS Laboratories would wind down standalone grading operations. The official reasoning was the difficulty of sustaining a second standalone lab at scale; the practical reasoning included the gravitational pull of GIA's pricing-benchmark position.

Late 2022 — operations cease. AGSL issued its last standalone AGS Platinum Light Performance Diamond Quality Documents and the Las Vegas facility transferred to GIA under an acquisition agreement. The grading software, the ASET methodology, the AGS Performance Grading Standard IP, and the research staff — including senior cut researchers — moved with the building. The agslab.com historical report-lookup database was preserved and is now archived under GIA.

2023 — AGS Ideal Report launches inside GIA. GIA introduced the AGS Ideal Report as a digital supplement that attaches to an eligible GIA Diamond Grading Report or GIA Laboratory-Grown Diamond Report on qualifying rounds and select fancy shapes, for roughly $25 per stone. The scoring criteria are the same AGS Performance Grading Standard the old AGS Platinum reports used; the supplement prints AGS 0 on stones that pass.

2024–2026 — the trade settles. Informed trade buyers treat a pre-2022 AGS Platinum report at parity with GIA equivalents on naturals. Retail counters that don't recognize the AGS name post-closure commonly discount or send the stone to GIA for fresh paper. The American Gem Society trade association continues to operate as a separate non-profit; an "AGS member jeweler" credential post-2022 is about retailer ethics, not lab grading.

The 0 to 10 cut-grade chart, in plain English

Lower is better, and the same 0–10 scale also runs the polish, symmetry, color (where 0.0 = D), and clarity (where 0 = FL) lines on the same report. The cut-specific chart, with the GIA equivalent the trade uses to translate:

AGS cut grade	AGS label	What it actually means	Rough GIA cut equivalent
0	Ideal	Brightness, contrast, dispersion, and leakage all in the top performance bucket under ASET; proportion, polish, and symmetry also at 0 (often written AGS 000 for triple-zero). The top 10–15% of GIA Triple Excellents.	GIA Excellent + AGS Ideal 0 supplement on the same stone
1	Excellent	One tier below Ideal — typically a measurable leakage band or minor contrast asymmetry; visually almost identical to AGS 0 to a non-trade eye.	GIA Excellent (without AGS 0)
2	Very Good	Roughly the middle of the GIA Excellent proportion band with one or two metrics measurably softer.	GIA Excellent (low end) to GIA Very Good
3	Good	Proportions or polish/symmetry visibly off-target; leakage or weak contrast starts to show in the ASET image.	GIA Very Good to low GIA Good
4	Fair	Material leakage or proportion mismatch; the stone is functional but visibly underperforming.	GIA Good to GIA Fair
5	Poor	First clearly poor tier.	GIA Fair
6	Poor	Pronounced leakage or proportion error.	GIA Poor
7	Poor	Same.	GIA Poor
8	Poor	Same.	GIA Poor
9	Poor	Same.	GIA Poor
10	Poor (bottom of scale)	Worst-case grade printable.	GIA Poor

The AGS 0 vs AGS 1 gap is where the dollars live. On a 1.00-ct round natural at a $7,500/ct retail comp, an AGS 0 verdict typically commands a 3–7% cut premium over an AGS 1 on the same color and clarity — even though a non-trade observer cannot reliably tell the two stones apart at arm's length. The premium pays for verified light performance, not for visible difference, and that is the whole point of the AGS scale.

For how the per-carat numbers anchor, the live 2026 diamond price-per-carat index carries the round and fancy-shape bands by carat, color, and clarity that an AGS 0 premium attaches on top of.

How to read a legacy AGS Platinum Light Performance report

A pre-2022 AGS Platinum Light Performance Diamond Quality Document — the standard form factor from 2005 onward — has four blocks. Read them in this order.

1. Header block. Top of the document. Carries the report number, issue date, lab address (always Las Vegas, USA), and a one-line stone description (shape, weight, measurements). The report number is the verification handle: write it down before doing anything else and look it up at agslab.com, which redirects to the historical-database archive now hosted under GIA. If the number does not return a record, the paper is fabricated or has been altered.

2. Performance Grading block. The headline. Three lines:

Cut grade — 0 to 10. This is the AGS cut grade most buyers think of when they hear "AGS 0." It is the combined light-performance verdict.
Polish — 0 to 10. Surface-finish quality at the facet level.
Symmetry — 0 to 10. Facet alignment and meeting-point precision.

A stone labeled AGS 000 on the report means 0 cut + 0 polish + 0 symmetry — the triple-zero verdict the trade pays a premium for. Anything other than three zeros and the stone is one step or more below the top tier; check which line slipped.

3. 4Cs block. Four lines, all on the same 0–10 numeric scale:

Color — 0.0 to 10.0 in 0.5-point steps. 0.0 ≈ GIA D, 0.5 ≈ E, 1.0 ≈ F, 1.5–2.0 ≈ G, 2.5 ≈ H, 3.0–3.5 ≈ I, 4.0 ≈ J, 4.5–5.5 ≈ K–M, 6.0–7.5 ≈ N–R, 8.0–10.0 ≈ S–Z.
Clarity — 0 to 10 in 1-point steps. 0 = FL, 1 = IF, 2 = VVS1, 3 = VVS2, 4 = VS1, 5 = VS2, 6 = SI1, 7 = SI2, 8 = I1, 9 = I2, 10 = I3.
Carat weight in standard decimal carats (unchanged from GIA convention).
Measurements in millimeters (min × max × depth).

4. Diagrams and ASET image block. Back of the report. Three artifacts:

The proportion diagram — table %, depth %, crown angle, pavilion angle, girdle thickness, culet size, polish/symmetry callouts. Identical in spirit to GIA's diagram block.
The clarity plot — a top-down map of inclusions, with internal characteristics in red and surface blemishes in green, matching the lab-standard symbol set.
The ASET image — the red/green/blue hemisphere image showing where the stone returns brightness (red), holds contrast (green), and leaks light (white). This is the proprietary AGS visual that no GIA-only report carries. Strong even red with controlled green contrast and minimal white is what AGS 0 light performance looks like. Large white patches anywhere in the table or near the girdle indicate measured leakage.

The verification checklist. Before treating any pre-2022 AGS Platinum report as valid:

Match the laser-inscribed report number on the girdle to the number printed on the paper. Use a 10x loupe or a microscope; the inscription is real but small.
Look up the same number at agslab.com and confirm the returned grades match the document in your hand.
If the stone is being sold to you, ask the seller for a current GIA report as well — a fresh GIA grading on the same stone, ideally with the AGS Ideal supplement attached, is the cleanest 2026 paper trail. The legacy AGS document still anchors provenance, and the new GIA + AGS Ideal pair carries forward the same cut verdict on currently-issued paper. For the line-by-line GIA walkthrough, see how to read a GIA diamond report and reading a GIA laser inscription.

How GIA actually absorbed the methodology

This is the part most write-ups get wrong. GIA did not "fold AGS into its own cut grade." GIA's own cut grade — Excellent through Poor on proportion measurements plus polish, symmetry, and a face-up appearance check — was unchanged by the acquisition. What GIA did was bolt the AGS Performance Grading Standard onto the side of the existing GIA report as a separately-priced supplement.

The mechanics, in order:

The software moved. The ray-tracing engine, the AGS-proprietary scoring layer on top, and the ASET imaging pipeline all transferred to GIA's Carlsbad infrastructure.
The research staff moved. Senior AGS cut researchers transferred to GIA roles, carrying the institutional knowledge of how the standard was tuned, why specific thresholds sat where they did, and which edge cases had historically been the hard calls.
A new product wrapper launched. GIA released the AGS Ideal Report as a digital, QR-linked supplement to a GIA Diamond Grading Report (or GIA Laboratory-Grown Diamond Report). The customer pays roughly $25 per stone on top of the base GIA report fee. The supplement runs the stone through the same AGS Performance Grading Standard the legacy AGS Platinum reports used and prints a 0 verdict for stones that pass.
The standalone AGS Platinum report stopped. No new AGS Platinum Light Performance Diamond Quality Documents have been issued since late 2022. The supplement is the only living format the methodology now ships in.
The historical database stayed open. agslab.com still resolves report-number lookups against pre-2022 paper. The data is preserved and accessible.

What this means for a buyer in 2026: a stone that earns AGS 0 on a freshly-issued GIA + AGS Ideal supplement is, methodologically, the same verdict the same stone would have earned from AGS Laboratories in 2021. Same software, same standard, often the same human researchers reviewing edge cases. The supplement is the new wrapper for the same science.

Legacy AGS report value: what your pre-2022 paper is actually worth

Three cases, all anchored to dollars rather than principle.

Case 1 — a pre-2022 AGS Platinum 0 round natural sold to an informed trade buyer. Parity with GIA Triple Excellent + AGS Ideal 0 supplement on the same stone. The trade recognizes the credential, the lookup at agslab.com confirms the grade, and the price reflects the cut verdict.

Case 2 — the same stone sold to a non-trade retail buyer through a counter that doesn't recognize the AGS name post-closure. Expect a 5–10% discount for paper unfamiliarity, or budget the cost of pulling a fresh GIA report (roughly $80–$200 depending on weight) plus the $25 AGS Ideal supplement to convert the verdict to current paper. On a $7,500/ct comp this is a $375–$750 swing per carat — material on a 1.5-carat or larger stone, not on a 0.5-carat one.

Case 3 — a pre-2022 AGS 0 on a signed-cut branded round (Hearts on Fire, Whiteflash A CUT ABOVE, A. Jaffe, original Eightstar). Trade buyers who know the brand will pay the original AGS 0 premium plus the brand premium. Retail buyers without brand familiarity often won't. The brand context decides whether the AGS paper is doing useful work in the sale.

Numbers, for a 1.00 ct round, GIA G/VS1 Triple Excellent equivalent, $7,500/ct retail comp:

Original pre-2022 AGS Platinum 0 paper, sold to a trade buyer who recognizes it: $7,500/ct, parity with GIA.
Same paper sold to a non-trade retail buyer: $6,750–$7,125/ct (5–10% discount).
Same stone re-papered as GIA Triple Excellent + AGS Ideal 0 supplement: $7,725–$8,025/ct (3–7% premium).
Same stone with only the GIA Triple Excellent report (no AGS Ideal supplement added): $7,500/ct.

The cleanest path for a private seller in 2026: keep the original AGS Platinum report as provenance, but pay the $105–$225 round-trip to attach a current GIA + AGS Ideal pair before listing. The buyer gets currently-issued paper, the trade verdict on the cut stays intact, and the discount disappears.

What to ask before buying a stone with AGS paper

A short script for any 2026 transaction involving an AGS-graded stone:

"Is this a pre-2022 AGS Platinum Light Performance report, or a current GIA + AGS Ideal supplement?" — establishes which document format you are looking at.
"What is the report number, and may I verify it against the agslab.com historical database (for pre-2022 AGS paper) or against GIA Report Check (for current GIA + AGS Ideal)?"
"Does the laser-inscribed number on the girdle match the paper?" Verify with a loupe before money moves.
"For a pre-2022 AGS 0 stone — has a fresh GIA report been pulled, or will the seller pull one? The AGS Ideal supplement is $25 on top of a current GIA report and forward-carries the cut verdict on currently-issued paper."
"Show me the ASET image from the report." On a pre-2022 AGS Platinum the image is printed on the back; on a current GIA + AGS Ideal it is in the digital supplement. Strong red, controlled green, minimal white = the verified AGS 0 light pattern. Large white patches near the table or girdle = measured leakage; the cut grade should already reflect this, but verify with your own eye.

The one-line summary

AGS Laboratories printed standalone cut paper from 1996 to 2022 on a continuous 0–10 light-performance scale where 0 is Ideal; the lab closed in late 2022 but the methodology survives as the $25 AGS Ideal supplement on a current GIA report — same software, same standard, same scientists, new wrapper. A pre-2022 AGS Platinum 0 stone is still a real AGS 0 stone; convert the paper for the cleanest resale, keep the original for provenance. For the head-on AGS-versus-GIA decision on a stone you are buying today, see AGS vs GIA: side-by-side grading rubric and the full methodology hub at AGS vs GIA: cut grade and when each matters. For the three-lab decision that adds IGI, see GIA vs IGI vs AGS. For where AGS 0 fits inside the broader cut-quality picture, see diamond cut grade explained and GIA cut grade comparison.