Premium Cut
Premium Cut
The proprietary cut grade between Very Good and Ideal in non-GIA diamond grading systems
Premium Cut is a cut-quality grade used in some diamond grading systems and trade-parlance contexts, positioned between Very Good and Ideal — or between Excellent and Ideal in systems that use both terms — and indicating excellent proportions, symmetry, and polish with strong light return. The grade is not part of the GIA cut-grade scale, which uses Excellent as its top grade for round brilliants. Premium appears principally in proprietary retailer grading programmes and in informal trade descriptions, and is most often encountered as a label on round brilliants priced one tier below the top of a given retailer's grading scheme.
Origin of the term
The Premium designation grew out of the period before the GIA introduced its formal cut-grade system in 2006. During the preceding decades, several diamond retailers and grading networks developed proprietary cut classifications that ranked round brilliants on combinations of proportion, symmetry, and polish. Premium served as the second-from-top tier in several of these systems, sitting below proprietary Ideal grades and above the conventional Very Good tier. The term has persisted in marketing usage even after GIA's grading system became the industry standard.
The American Gem Society (AGS) operates a parallel cut-grading system independent of GIA's, using a 0-to-10 numerical scale where 0 is the top tier (AGS Ideal). AGS does not use Premium as a formal designation; references to Premium typically point to non-AGS proprietary systems or to general retail parlance.
What the grade typically describes
A Premium-grade round brilliant typically exhibits proportions within the upper portion of GIA's Excellent range, with table size, depth, crown angle, and pavilion angle within the windows that produce strong light return. Symmetry is high — facet alignment, table-girdle parallelism, and overall outline regularity are at the level expected of a polished commercial stone. Polish is correspondingly high, with no visible polish lines or burn marks under standard grading magnification.
The distinction between Premium and the proprietary Ideal grade above it usually rests on small differences in proportion: a Premium stone may have a slightly thicker girdle, a marginally less optimal table-to-depth ratio, or symmetry deviations of a magnitude that would not affect face-up appearance to a non-specialist viewer. The differences are most often academic for the wearer and most relevant to the dealer in pricing and inventory categorisation.
Use for fancy shapes
Premium designations are sometimes applied to fancy shapes — princess, cushion, oval, emerald, and so forth — where the GIA Excellent grade does not formally extend. Fancy-shape proportions are not subject to a single mathematical optimum in the way that round brilliants are, and proprietary Premium grades for fancy shapes typically reflect the retailer's internal judgement about face-up appearance and proportion rather than reference to a published standard.
Buyers should treat Premium grades on fancy shapes with the appropriate scepticism: the term has commercial meaning within the issuing retailer's system but does not necessarily transfer to other contexts. A Premium oval at one retailer is not necessarily comparable to a Premium oval at another.
Pricing implications
Premium-grade round brilliants typically trade 5 to 10 per cent below comparable Ideal or Excellent stones at the same colour, clarity, and weight. The discount reflects the small but real proportional differences and the dealer-side recognition that a Premium stone is one tier short of the optimum. For retail buyers, the Premium grade often represents a reasonable trade-off: face-up appearance close to the top tier at a measurable discount.
In the trade
Modern trade practice favours GIA cut grades — Excellent, Very Good, Good, Fair, Poor — for round brilliants, with Premium retained mainly in proprietary retail systems. Buyers comparing diamonds across multiple sources should ask which grading authority issued the cut grade and on what scale; a Premium-graded stone with no GIA report behind it is a different proposition from a GIA Excellent stone, and the price difference between the two often reflects the difference in graded authority rather than the difference in cut quality.