Each cut page on The Cut Guide presents a comprehensive reference for a single diamond or gemstone shape — its geometry, optical properties, specifications, and history. Reading one takes about three minutes. Using one well takes understanding what each section is actually telling you and how the pieces fit together into an informed buying decision.
None of our cut pages are written to sell anything. They exist to give you the same information a knowledgeable gemologist would share before you walked into a showroom — and to give it to you in a form you can return to as many times as you need.
| Section | What it shows | How to use it |
|---|---|---|
| Header | Cut name, origin, facet count, primary use case | Orientation — confirm you're reading the right shape and understand its category |
| Brilliance score | White light return relative to other cuts; 0–100 scale | If light return is your priority, prefer scores above 80. Round tops the scale at ~98. |
| Fire score | Colored dispersion (spectral flash) relative to other cuts | If fire and color play are important, look for scores above 60. Asscher and radiant are high-fire step/hybrid cuts. |
| Scintillation score | Movement-driven sparkle; combines flash points and pattern contrast | Brilliant cuts score highest. If you'll wear in motion or low light, prioritize this score. |
| Size per carat | Apparent face-up area relative to round for the same carat weight | Elongated shapes (marquise, pear, oval) appear larger per carat than round. If visual size matters, consult this score alongside actual mm dimensions. |
| Depth % range | Ideal and acceptable depth percentage for this shape | Check the grading report. If the stone is outside the ideal range, ask why — it may be optimized for weight, not appearance. |
| Table % range | Ideal table proportion for this shape | Works in concert with crown angle for rounds. For fancy shapes, use as a sanity check — outside the range suggests disproportionate cutting. |
| Cut grade callout | Whether GIA grades this cut's quality; what to use instead | For rounds, confirm GIA Excellent or AGS 0. For fancy shapes, this callout will explain the evaluation alternatives. |
| Facets callout | Total facet count and structure notes | Context for the scintillation character — more facets generally means more flash points; fewer facets means larger reflections. |
| Clarity minimum callout | Eye-clean clarity floor for this shape | Step cuts require VVS territory; brilliant cuts can go to SI1 in many cases. Use this before setting a clarity budget. |
| Originator section | Who developed the cut and when | Context — understand where the design came from and why it exists in its current form. |
| Buying note | Shape-specific risks and what to watch for | The most practical section for active buyers. Read this before you visit a retailer or contact an online vendor. |
The brilliance, fire, and scintillation scores on each cut page are comparative, not absolute. They rank cuts against each other based on their optical character under typical conditions. They do not predict how bright a specific stone will appear in a specific room under specific lighting — no reference guide can do that without examining the individual stone.
Use the scores to understand trade-offs. A cushion cut scores lower on brilliance than a round brilliant, but higher on fire than most other shapes. That tells you something useful: a cushion is a good choice if you value color play and can accept slightly less overall brightness. An emerald cut scores lower on both scintillation and brilliance but produces reflections that are distinctive and that some buyers prefer strongly. The scores don't tell you which cut is "best" — there is no best, only best for a specific buyer with specific preferences.
Two numbers that matter more than scores are the actual millimeter dimensions of the stone you are considering, and the depth percentage reported on the grading certificate. The dimensions tell you the true face-up size. The depth percentage tells you how much of the carat weight is actually sitting above the setting where you can see it. These are verifiable facts about a specific stone; optical scores are characteristics of a cut style.
A cut page is a starting point, not a buying guide. Use it to understand what a specific shape is and how it behaves optically before you start shopping. Use the specification ranges to evaluate stones on a grading report. Use the buying note to understand what to watch for in that specific shape. Then evaluate the actual stone — or have it evaluated — using the tools and knowledge you came here to build.
Once you know what you're reading, drop your cert into the Cert Checker — it reads the proportion data and flags how the cut stacks up.
Open the Cert Checker →