AGS Ideal-0

AGS Ideal-0 (sometimes written AGS 000) is the top tier on the AGS Performance Grading Standard — the cut grade originally issued by AGS Laboratories and now available as a supplement to GIA Diamond Grading Reports following GIA's 2022 acquisition of the AGS science. A stone earns AGS Ideal-0 by scoring zero (the best score) on all four AGS metrics: Light Performance, Proportion Factor, Polish, and Symmetry.

The AGS scale runs 0 to 10, where 0 is Ideal, 1 is Excellent, 2 is Very Good, and so on down to 10 (Poor). Each metric is graded independently and the worst score sets the overall grade. A stone with 0/0/0/1 is an AGS 1 Excellent, not an AGS 0 Ideal — the system does not average. The strictness is what makes AGS Ideal-0 a tighter claim than GIA Excellent Cut: GIA's Excellent grade is a single bucket that admits a range of proportions and light performance levels; AGS Ideal-0 requires zero across every measured axis.

The Light Performance metric is the AGS innovation. It is graded by ray-tracing the actual stone (not its proportion summary) and measuring four outputs: brightness, contrast, dispersion (fire), and leakage. AGS Ideal-0 requires top-of-standard brightness, controlled contrast, strong dispersion, and minimal leakage. The grading is paired with ASET imaging — the colour-coded hemisphere image that visualises where light is arriving from and where it is leaking.

The Proportion Factor metric grades the underlying geometry — crown angle, pavilion angle, table %, depth %, girdle thickness, star length, lower-half length. AGS Ideal-0 requires every proportion to fall inside the AGS Ideal band. The bands are tighter than GIA Excellent: AGS Ideal-0 crown angle runs 34.0° to 35.0° vs GIA Excellent's 33.5° to 35.5°.

AGS Ideal-0 routinely shows hearts-and-arrows symmetry because the Symmetry grade alone is tight enough to enforce H&A. The combination of Ideal-0 paper plus visible H&A defines the "super ideal" tier the trade prices at a 5% to 15% premium over GIA 3EX without an AGS supplement.

Since AGS Laboratories closed in 2022, AGS Ideal-0 is available as the AGS Ideal Report supplement on qualifying GIA Diamond Grading Reports for roughly $25 per stone. The science is identical; the issuing entity is now GIA. Standalone pre-2022 AGS Platinum reports still trade at par.