Are Diamonds a Good Investment? Resale Value, Trade-Ups and What Holds Its Sparkle
Diamond education · Value & resaleAre diamonds a good investment? Resale value, trade-ups and what holds its sparkleA client walked into our...
Super Ideal Cut Diamonds vs Triple Excellent: The Truth
If you’re spending five figures on a diamond, you want to know it’ll actually sparkle. Not just look good on paper with a GIA certificate, but perform in real light, on a real hand, in real life.
That’s where the ASET vs Ideal-Scope debate comes in. These are the two most widely used tools for assessing diamond light performance, and they’re fundamentally different in what they reveal. One provides nuanced, colour-coded data across three lighting angles. The other offers brutal simplicity: pass or fail.
Holloway Diamonds has a unique perspective on this comparison. Our founder, Garry Holloway, invented the Ideal-Scope and was independently developing the principles behind angular light-performance assessment at the same time as Al Gilbertson in the United States. Both tools were created to solve the same fundamental problem: a grading certificate alone cannot tell you exactly how a diamond will perform with light.
Here’s what most jewellers won’t tell you: you don’t necessarily need the more complex tool to make the right decision.
Quick answer
- Ideal-Scope uses a hot pink reflector to show light return (red), obstruction (black) and leakage (white). It’s simple, decisive and excellent for rounds.
- ASET uses three colours (red, green, blue) to map light angles from 0–90°, revealing intensity and direction. It’s best for all other shapes.
- For rounds: either tool works. Ideal-Scope is faster and easier to interpret.
- For fancy shapes: ASET is non-negotiable.
- 90% of diamonds fail both tests — which is why most jewellers don’t use them.
What ASET actually measures
The ASET (Angular Spectrum Evaluation Tool) scope doesn’t just show if light returns — it shows where that light is coming from and how intensely. Place a diamond under an ASET scope and you see a colour-coded map:
Red
45–75°
The sweet spot. Light from directly above you, where most light comes from — the brightest, most valuable light for brilliance. More red means more punch.
Green
0–45°
Lower-angle light from the periphery and windows. Less intense than red, but still contributing — it adds balance and can enhance fire in certain cuts.
Blue
75–90°
Obstruction. Your head and body block light, creating contrast. Blue isn’t bad — it’s essential for scintillation, the sharp flashes when you move your hand.
White
Leakage
Backlighting shows where no light can be reflected. It’s wasted light escaping through the pavilion instead of reflecting to your eye.
The ASET concept was concurrently discovered by Garry Holloway and Al Gilbertson in the USA. In 2005 the American Gem Society (AGS) based its performance-based grading system on the tool, naming it the Angular Spectrum Evaluation Tool — a three-dimensional analysis that measures all 58 facets, not just 17 like traditional GIA cut grading. Garry Holloway manufactures the ASET scope for the AGS.
Why that matters
Two diamonds with identical depth percentages and table sizes can perform completely differently. ASET reveals those differences by mapping how each facet interacts with light at different angles. It’s the closest thing we have to predicting real-world performance from a static image.
The ASET scope comes in Garry’s handheld version (ASET 30, simulating 30° of head obstruction) and digital ray-traced versions produced from a 3D scan of the diamond’s facets. Professional vendors use these setups for consistent, high-quality images — the ones you’ll see alongside $20,000 cushion and emerald cuts.
What Ideal-Scope actually measures
Ideal-Scope is elegantly simple. It’s a hot pink-red reflector cone and a viewing lens. That’s it. When you look at a diamond through an Ideal-Scope:
Red
Light returns effectively to your eye. Darker red means more intense return — this is what creates brilliance.
Black
Obstruction from your head and body. Arrows and triangles that move with the stone are critical for scintillation. An all-red diamond looks flat.
White
Light leakage. Windows where light escapes rather than bounces back. This is your red flag.
1986
Garry Holloway invents the Ideal-Scope — a portable version of Okuda’s desktop Fire Scope from the 1970s.
The Ideal-Scope is the perfect rejection tool — something professionals and consumers can use to quickly eliminate poor performers from diamond parcels. And that’s still its best use: binary decision-making. Does this diamond return light effectively? Are there major leakage issues? Are there persistent dark zones like bow ties in oval, marquise and pear shapes?
The Ideal-Scope includes a 10x magnifying lens. With practice, you can read optical symmetry from the same arrow patterns shown through a hearts and arrows scope — with the added benefit of clearly indicating light leakage.
It’s intuitive. Show someone a saturated red image with sharp black arrows, and they instantly understand that’s good. Show them a washed-out pink image with white splotches, and they know it’s bad. You don’t need gemological training to interpret the basics.
Head to head: ASET vs Ideal-Scope
Let’s be direct about what each tool actually does better.
Round brilliants
Rounds are mathematically predictable. An Ideal-Scope image confirms the proportions are sound without needing to understand the complex relationships between table size, crown and pavilion angles.
ASET adds data, but for a well-cut round it confirms what Ideal-Scope already showed — a well-polished round shows little or no green. It can be the tiebreaker between two similar rounds, but it’s rarely necessary.
Fancy shapes
Princess, cushion, emerald, radiant, oval and pear shapes are far more complex. Their pavilion angles vary across the stone. An Ideal-Scope image often shows uniform red that looks perfect but misses critical detail.
ASET reveals where light angles are optimal (red), acceptable (green) and where contrast sits (blue). An oval or cushion with mostly green under the table shows clearly in ASET — Ideal-Scope might show it as solid red.
Speed
Any buyer can assess an Ideal-Scope image in 10 seconds: red is good, white is bad, check for symmetry, done. ASET means reading three colours, assessing distribution and checking blue forms symmetrical patterns — not complicated, but slower.
Precision
ASET provides granular data Ideal-Scope can’t capture. The distinction between 45° and 75° lighting angles matters, especially for fire and scintillation. ASET shows it; Ideal-Scope collapses it into “red”.
Availability
Most jewellers don’t use either, because almost all their diamonds would fail. From performance-focused online vendors, ASET images are standard for anything over $10,000. Ideal-Scope is more common as a handheld tool for in-person inspections.
When ASET is superior
Non-negotiable in three scenarios.
01
Fancy shapes
Anything other than a round brilliant, demand ASET. A “crushed ice” cushion might show perfect red in Ideal-Scope but uneven light distribution in ASET — which means inconsistent sparkle in real wear.
02
High-value stones
Spending $30,000+ on a 2-carat stone, you want every data point: intensity of brilliance, quality of fire and balance of contrast. You’re buying measurable light performance. ASET quantifies it.
03
Near-identical stones
Two cushions, both with excellent Ideal-Scope images, HCA under 2.0 and great videos. ASET shows which has more dominant red, better green distribution and cleaner blue symmetry — the tiebreaker between good and exceptional.
When Ideal-Scope is enough
Sufficient — and often preferable — when:
01
Rounds with solid proportions
A 1-carat round with a 34.5° crown, 40.8° pavilion, 57% table and a saturated red Ideal-Scope image? ASET won’t add actionable information. Move forward.
02
In-person evaluation
Bring a handheld Ideal-Scope ($25–65) and assess five diamonds in two minutes. Handheld ASET scopes are also available at ideal-scope.com for $50.
03
Budget constraints
Under $5,000 you’re screening for problems — leakage, poor symmetry, obvious cut deficiencies. ASET’s granular data matters most when you’re optimising for excellence.
04
Quick rejection
Ten stones. Eight show white leakage or washed-out pink — rejected. Two show strong red — shortlisted. The fastest way to separate contenders from pretenders.
What they don’t tell you
Here’s the part most diamond guides skip.
Truth 01
Neither tool is a complete picture
Diamond light performance is three-dimensional: brilliance (white light return), fire (coloured light dispersion) and scintillation (sparkle and contrast). ASET maps brilliance and shows where contrast forms. Ideal-Scope confirms brilliance and reveals basic contrast patterning. Neither directly measures fire.
Fire is primarily determined by crown angles. A diamond with perfect scope images but a shallow crown (under 32°) will have weak fire — which is why scope images should be used alongside crown angle, pavilion angle, depth and table. The proportions predict fire. The scope images confirm brilliance and contrast.
Truth 02
Most retail diamonds would fail both tests
Ask a typical chain jeweller to show their diamonds under an Ideal-Scope. Watch them politely decline, or claim they “don’t need specialised tools”. The majority of their inventory would show leakage or poor contrast — pavilion angles too steep (41.2°+) creating windows of lost light, or too shallow (40.0°) looking dark up close.
<5%
of polished stones are super-ideal (AGS 0 or HCA under 2.0)
3–4x
longer to cut — so mass-market jewellers can’t stock them profitably
Retailers rely on super bright lighting, marketing, and the fact that most buyers have no performance baseline. So they don’t stock super-ideals — and they certainly don’t use tools that would expose it.
Truth 03
Photoshopped ASET images exist
At the high end, ASET images are occasionally manipulated — facets cleaned up, colours intensified, symmetry perfected. Compare the ASET image to photos and videos of the same diamond. Do the facet patterns align? Do imperfections visible in photos mysteriously disappear in the ASET? That’s your warning.
Reputable vendors of designer jewellery in Melbourne don’t need to Photoshop, because their stones are genuinely well cut. Be wary of unknown sellers offering “perfect” ASET images at below-market prices.
Truth 04
Scope images require proper lighting
Too much backlight and leakage washes out, appearing less severe than it is. Too little and everything looks dark. Professional vendors use standardised setups — ASET with controlled backlight, or ideal-light devices for Ideal-Scope. A desk lamp behind a piece of paper? Inconsistent.
If you’re using a handheld scope yourself, your image may look different from the vendor’s — and that’s okay, as long as you’re comparing consistently lit images.
What this means for you
Let’s bring it back to what actually matters: brilliance, fire, scintillation. You’re not buying an ASET image. You’re buying a diamond that performs in boardrooms, at outdoor weddings and under office lighting. Scope images are predictive tools, not the end goal. Here’s how to use them properly.
01
Filter by proportions first
Use the Holloway Cut Adviser (HCA) as a rough filter for round brilliants: scores under 2.0 are worth reviewing; over 2.0 can be rejected. It’s not definitive, but it eliminates obvious poor performers.
02
Request Ideal-Scope or ASET images
For rounds, either is fine. For fancy shapes, insist on ASET. If the vendor can’t or won’t provide scope images, walk away — there’s no legitimate reason to hide this data unless the diamond’s light performance is poor.
03
Interpret the images in context
A round with strong Ideal-Scope saturation — dark red, minimal white, sharp black arrows — is excellent. For a fancy shape, look for this ASET balance:
Red
40–60%
Green
20–30%
Blue
15–30%
White
Minimal
If you see significant white or washed-out zones, or unbalanced blue patterns, reject it.
04
View the actual diamond, or videos
Scope images predict performance; they don’t replace visual confirmation. Watch videos in different lighting and ask for outdoor shots (not in direct sunlight). If the videos look dull despite perfect scope images, something’s off.
05
Trust measurable data, not marketing
“Hearts and Arrows” branding doesn’t guarantee light performance. “GIA Triple Excellent” doesn’t mean super-ideal — it means the diamond met minimum thresholds across three categories. Use the tools. Don’t rely on words.
90%
rejection rate when GIA Triple Excellent diamonds are put under an Ideal-Scope.
The bottom line
Round diamonds
Ideal-Scope is sufficient
Faster, simpler, and reveals the leakage issues that matter most. Ideal proportions and a clean image? You’re done.
Fancy shapes
ASET is superior
Non-round cuts demand angle-specific light analysis. Don’t compromise on this.
$20,000 and above
Get both
Ideal-Scope for quick assessment, ASET for precision. You’re investing serious money — maximise your data.
The broader truth
No scope images, no sale
If a jeweller refuses to provide scope images or calls them “unnecessary”, you’re being sold a performance-compromised stone.
This debate isn’t about one being categorically “better”. It’s about using the right tool for the job.
Want to see this in practice? Visit the Holloway Diamonds showroom and speak with one of our diamond specialists. We’ll show you Ideal-Scope and ASET images side by side, explain what you’re looking at, and make sure you’re buying measurable light performance. For bespoke designs, including Melbourne custom jewellery and rare coloured stones such as Argyle pink diamond engagement rings, we assess every stone using both tools before it’s set.
Because at this price point, you deserve to know exactly what you’re buying.
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