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Our Philosophy: Redefining "Ideal"
Perfection isn’t a single number - it’s a harmony of proportions, symmetry, and feeling.
Where Marcel Tolkowsky helped define the ideal for rounds on paper, Osiris Diamonds re-interprets that vision for real diamonds, in real lighting, and across every popular
shape.
The Osiris Ideal™ - geometry guided by science, perfected by sight.
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How We Define Ideal for Every Shape
Most jewelers talk about “ideal cut” only for round diamonds, often pointing back to Marcel Tolkowsky’s 1919 work balancing fire and brilliance. Over time, labs and researchers refined those ideas - but for fancy shapes like ovals, cushions, and radiants, there is still no single, universal standard.
At Osiris Diamonds, we build on that original light-performance theory and modern research to create something more practical: a performance-based system we call the Osiris Ideal™. Instead of relying on one set of angles, every shape is judged
through a blend of geometry, light-performance analysis, and expert visual review.
Our Evaluation Process for Every Diamond
Every Osiris Ideal™ diamond must pass two key benchmarks under my personal
supervision
Precision Proportion Range
Each diamond is meticulously selected within strict,proven proportion windows that balance brilliance, fire, and face-up size.
View Our Detailed Ideal Ranges for All Shapes Below ↓
Light-Performance Verification
Each diamond is then rigorously evaluated
using advanced imaging and my personal visual inspection to confirm:
minimal light leakage
strong, even brightness
pleasing contrast patterning with minimal bow-tie (where applicable)
Only diamonds that pass both my precise numerical standards and my final, in-house
visual performance check earn the Osiris Ideal™ designation.
The Osiris Ideal™ Round: Precision You Can See
Precision you can see — brilliance you can feel.
Every Osiris Ideal™ Round is cut to an exacting set of proportions that balances fire, brilliance, and scintillation — the kind of light performance only the very best round brilliants achieve. The philosophy comes from Marcel Tolkowsky’s original 1919 “ideal cut” theory, refined by modern light-performance research and my own real-world testing. In practice, that means keeping each diamond inside a narrow, proven sweet spot:
Round Cut Note
Round brilliants have the most standardized facet architecture, so crown and pavilion angles are meaningful predictors of light performance. Osiris Ideal™ uses tight proportion targets for rounds, then confirms with video and optical symmetry.
| Parameter | Ideal Range | Sweet Spot |
|---|---|---|
| Table % | 54 – 57% | 55% |
| Depth % | 60.6 – 62.2% | 61.8% |
| Crown Angle | 34.0° – 35.0° | 34.5° |
| Crown Height % | 14 – 16% | 15% |
| Pavilion Angle | 40.6° – 40.9° | 40.8° |
| Pavilion Depth % | 42.8 – 43.2% | 43% |
| Lower Girdle % | 75 – 80% | 77% |
| Star Length % | 50 – 55% | 52% |
| Girdle | Thin – Medium | — |
This harmony of geometry and polish directs light back through the crown, creating that rare mix of bold white flashes and rich spectral fire that defines a true high-performance
ideal cut.
Every diamond bearing the Osiris Ideal™ Round mark has been personally reviewed and approved by GIA-trained diamond expert Osiris Ramirez — so you’re not just buying a lab grade, you’re buying a stone chosen to deliver emotion in every sparkle.
Beyond Rounds: The Ideal for Fancy Shapes
While the science for round brilliants is well-established, defining "ideal" for fancy shapes like ovals, cushions, and radiants requires a nuanced approach. At Osiris Diamonds, we apply the same rigorous two-benchmark process—precision proportion
ranges and light-performance verification—to ensure every fancy shape diamond achieves its maximum beauty.
Because each fancy shape has its own unique characteristics and light interaction, our expert visual review is paramount. We focus on:
• Minimizing Light Leakage: Ensuring light is returned efficiently, avoiding dull or "dead" spots.
• Optimal Brightness & Fire: Maximizing the diamond's overall sparkle and flashes of color.
• Symmetry & Shape Appeal: Confirming the diamond's aesthetic balance and desirable outline.
• Addressing Bow-Tie Effect (where applicable): Meticulously selecting stones with minimal to no bow-tie effect, a common issue in elongated fancy shapes.
Every Osiris Ideal™ fancy shape diamond has not only met my precise numerical standards but has also undergone my personal visual inspection to confirm its exceptional real-world sparkle and beauty. This crucial final factor, performed inhouse, guarantees that every Osiris Ideal™ diamond truly lights up.
Osiris Ideal™ Cut Standards: The Specifics forEvery Shape
Premium | Realistic | Performant | Curated for Modern Cutting
For those who appreciate the precise details behind our commitment, here are the exact parameters that define an Osiris Ideal™ diamond across all shapes. Remember, these ranges are always complemented by our rigorous light-performance verification and my personal visual inspection, ensuring both scientific accuracy and breathtaking beauty.
(You might consider using interactive accordion elements for each shape table to keep the page visually clean, allowing users to expand only the shapes they are interested
in.)
Fancy Shape Method
Unlike round diamonds, fancy shapes vary significantly in facet architecture. That means crown and pavilion angles on lab reports are not always consistent predictors of beauty across all fancy cuts. Osiris Ideal™ uses proven proportion targets to shortlist stones, then confirms real-world performance through video review (and ASET/IdealScope when available).
OVAL — Osiris Ideal™
Bow-Tie & Lighting (Osiris Ideal™)
Bow-tie contrast can appear in elongated shapes, especially under harsh direct light. Osiris Ideal™ selects stones where the bow-tie remains minimal in everyday lighting and breaks up in motion—adding lively contrast rather than a static shadow.
| Parameter | Ideal Range | Sweet Spot |
|---|---|---|
| L/W Ratio | 1.30–1.50 | 1.35–1.45 |
| Table % | 54–63% | 57–60% |
| Depth % | 59–64% | 60.5–62.5% |
| Girdle | Thin–Slightly Thick | Medium–Slightly Thick |
| Bow-Tie | Faint – Minimal | — |
Performance note
- Bow-tie must be minimal in everyday lighting and break up in motion (faint bow-tie in harsh direct sun is normal)
- No windowing
RADIANT — Osiris Ideal™ (Updated for Modern Cutting)
Contrast & Banding (Osiris Ideal™)
Radiants can show central dark banding depending on facet architecture; Osiris Ideal™ selects stones where contrast stays lively and broken in motion—not mushy or static.
| Parameter | Ideal Range | Sweet Spot |
|---|---|---|
| L/W Ratio | 1.20–1.50 | 1.30–1.40 |
| Table % | 61–70% | 62–68% |
| Depth % | 64–70% | 65–68% |
| Girdle | Thin–Slightly Thick | Medium–Slightly Thick |
Performance note
- Radiants can show central dark banding depending on facet architecture; Osiris Ideal™ selects stones where contrast stays lively and broken in motion—not mushy or static.
CUSHION BRILLIANT / MODIFIED — Osiris Ideal™
Elongated Cushion — Osiris Ideal™ (Updated for Your Inventory)
| Parameter | Ideal Range | Sweet Spot |
|---|---|---|
| L/W Ratio | 1.05–1.30 | 1.15–1.25 |
| Table % | 56–68% | 58–64% |
| Depth % | 62–69% | 63.5–67% |
| Crown Height % | 13 – 16% | 15% |
| Girdle | Thin–Slightly Thick | Medium–Slightly Thick |
Performance note:
- No windowing / see-through areas
- Lively in motion (not flat/glassy)
EMERALD (STEP CUT) — Osiris Ideal™
Modern emeralds are cut deeper in today’s supply to maximize sparkle and minimize windowing, which is common in step cuts. This is your final, realistic premium range for breathtaking emeralds:
| Parameter | Ideal Range | Sweet Spot |
|---|---|---|
| L/W Ratio | 1.30–1.60 | 1.35–1.50 |
| Table % | 60–70% | 62–66% |
| Depth % | 62–70% | 64–68% |
| Crown Height % | 10 – 15% | 12–13% |
| Girdle | Thin – Thick | Medium–Slightly Thick |
Performance note:
- Minimal to no windowing in motion
- Crisp, even steps (“hall-of-mirrors”)
PEAR — Osiris Ideal™
Bow-Tie & Lighting (Osiris Ideal™)
Bow-tie contrast can appear in elongated shapes, especially under harsh direct light. Osiris Ideal™ selects stones where the bow-tie remains minimal in everyday lighting and breaks up in motion—adding lively contrast rather than a static shadow.
| Parameter | Ideal Range | Sweet Spot |
|---|---|---|
| L/W Ratio | 1.40–1.65 | 1.45–1.58 |
| Table % | 54–64% | 56–61% |
| Depth % | 59–65% | 60.5–63.5% |
| Crown Height % | 13 – 16% | 15% |
| Girdle | Thin–Slightly Thick | Medium–Slightly Thick |
| Bow-Tie | Minimal | — |
Performance note:
- Bow-tie minimal in everyday lighting and breaks up in motion
- No windowing
- Balanced symmetry
MARQUISE — Osiris Ideal™
Bow-Tie & Lighting (Osiris Ideal™)
Bow-tie contrast can appear in elongated shapes, especially under harsh direct light. Osiris Ideal™ selects stones where the bow-tie remains minimal in everyday lighting and breaks up in motion—adding lively contrast rather than a static shadow.
| Parameter | Ideal Range | Sweet Spot |
|---|---|---|
| L/W Ratio | 1.70–2.25 | 1.85–2.10 |
| Table % | 52–64% | 54–60% |
| Depth % | 57–63% | 58.5–61.5% |
| Crown Height % | 13 – 16% | 15% |
| Girdle | Thin–Slightly Thick | Medium–Slightly Thick |
| Bow-Tie | Minimal | — |
Performance note:
- Bow-tie must break up in motion (not a fixed dark stripe through the belly)
- No windowing
- Brightness stays lively along the body
Ready to Experience the Osiris Ideal™ Difference
Explore our curated collection of hand-selected diamonds, each certified to meet the Osiris Ideal™ Cut Standard and personally approved for exceptional beauty and sparkle.