Introduction
Every diamond carries an internal map of how it grew. The crystal lattice records its growth history in the form of sector boundaries, layer transitions, and defect distributions that are invisible to the naked eye and to standard gemological lighting. But under deep ultraviolet excitation, these internal structures fluoresce — and the resulting image reveals whether the diamond grew in the Earth's mantle, in an HPHT press, or in a CVD plasma chamber.
The DiamondView instrument, developed by the Diamond Trading Company (De Beers Group) and now standard equipment in major gemological laboratories, is the primary tool for this type of analysis. It produces fluorescence images that are among the most intuitive and definitive indicators of diamond origin.
How DiamondView Works
The Light Source
The DiamondView uses a deep-UV xenon flash lamp producing light below 225 nm — significantly shorter wavelength than standard long-wave UV (365 nm) or short-wave UV (254 nm). At these very short wavelengths, the excitation penetrates only a thin surface layer of the diamond, and the resulting fluorescence comes primarily from the growth structure immediately below the surface.
The Imaging Process
- The diamond is placed in the instrument's darkened chamber
- The xenon flash lamp fires, illuminating the diamond with deep-UV pulses
- A camera captures the fluorescence emitted by the diamond's internal structure
- Colour filters (blue at 390 nm, green at 475 nm, orange at 550 nm, red at 725 nm) can be applied to isolate specific fluorescence wavelengths and enhance structural detail
The result is a false-colour image showing the diamond's growth pattern — a visual fingerprint that differs fundamentally between natural and lab-grown diamonds.
Growth Patterns by Origin
Natural Diamonds
Natural diamonds crystallise primarily in octahedral habit, with growth occurring on the eight faces of the octahedron. Over billions of years, this growth produces:
- Irregular octahedral growth patterns — the growth history of a natural diamond is complex and variable, reflecting changing conditions over geological time
- Blue fluorescence in many specimens, from N3 nitrogen aggregate centres
- Asymmetric, organic-looking patterns — no two natural diamonds show identical growth structures
- Growth interruptions and restarts visible as discontinuities in the pattern
The irregular, non-repeating quality of natural growth patterns is itself diagnostic. Nature does not produce the geometric regularity of laboratory growth.
HPHT-Grown Diamonds
HPHT diamonds grow in cuboctahedral sectors — a combination of cube faces and octahedron faces radiating from the seed. Under DiamondView:
- Cross-shaped or geometric sector patterns — the cuboctahedral growth sectors appear as regular, symmetrical divisions within the stone
- Different fluorescence colours in different sectors — because trace elements (nitrogen, boron) incorporate at different rates into different growth sectors, each sector may fluoresce a different colour or intensity
- Highly regular, symmetrical geometry — the pattern looks engineered rather than geological
The cross-shaped sector pattern is one of the most recognisable DiamondView signatures. Even without spectroscopic analysis, an experienced operator can identify HPHT origin from the image alone.
CVD-Grown Diamonds
CVD diamonds grow layer by layer from a flat seed plate. Under DiamondView:
- Parallel banding or striations — horizontal lines running across the image, each representing a growth layer deposited from the plasma
- Uniform directionality — all features are oriented parallel to the seed interface, reflecting the one-directional growth of CVD deposition
- Possible fluorescence variation between layers — reflecting stop-and-start growth cycles and changing conditions between layers
The layered, directional quality of CVD patterns is distinctive. It looks fundamentally different from both the irregular patterns of natural growth and the geometric sectors of HPHT growth.
Visual Comparison
| Feature | Natural | HPHT | CVD |
|---|---|---|---|
| Pattern type | Irregular octahedral | Cross-shaped cuboctahedral | Parallel banding |
| Symmetry | Low (organic) | High (geometric) | Directional (layered) |
| Sector boundaries | Irregular or absent | Sharp, regular | Parallel lines |
| Fluorescence colour | Typically blue (N3) | Variable by sector | Variable by layer |
| Overall impression | Chaotic, complex | Structured, symmetric | Striped, directional |
Strengths and Limitations
Strengths
- Highly definitive. DiamondView patterns are among the most reliable identification indicators. The growth patterns are fundamentally different between natural and lab-grown and are difficult to misinterpret.
- Visually intuitive. Unlike spectroscopic data that requires interpretation, DiamondView images can be assessed visually. With training, pattern recognition becomes rapid.
- Reveals growth method. DiamondView distinguishes not only natural from lab-grown but also HPHT from CVD, based on the geometry of the growth pattern.
Limitations
- Expensive equipment. The DiamondView is a laboratory-grade instrument with a significant acquisition cost. It is not practical for retail bench use.
- Requires loose or partially mounted stones. The stone needs to be positioned in the instrument's chamber, which limits use with fully mounted jewellery.
- Operator training needed. While the patterns are visually distinctive, confident interpretation requires training and experience.
Access
DiamondView instruments are installed in major gemological laboratories (GIA, HRD, De Beers, and others) and at advanced diamond testing centres. Stones submitted for grading at these laboratories undergo DiamondView examination as part of the standard identification protocol.
For trade and retail settings, DiamondView analysis is available through laboratory submission services. It is typically the final confirmatory step after screening instruments have flagged a stone as "refer."
Frequently Asked Questions
Is DiamondView the most reliable identification method?
It is among the most reliable and visually compelling. Combined with spectroscopy (particularly PL), it provides near-certain identification for virtually all lab-grown diamonds. The two methods are complementary: spectroscopy identifies specific defect centres, while DiamondView visualises the growth structure.
Can DiamondView distinguish HPHT from CVD?
Yes. HPHT diamonds show cross-shaped cuboctahedral sector patterns, while CVD diamonds show parallel layered banding. The two patterns are visually distinct.
What if the pattern is ambiguous?
Ambiguous DiamondView patterns are rare but possible, particularly in unusual natural Type IIa diamonds or in diamonds with complex growth histories. In these cases, spectroscopic data (FTIR, PL) is used alongside the image to reach a conclusion.
Can a consumer request DiamondView imaging?
Consumers cannot typically access DiamondView directly, but they can submit diamonds to gemological laboratories that use the instrument. If a diamond is GIA-graded, it has already been examined with DiamondView as part of the standard grading process.
Summary
Fluorescence imaging with the DiamondView instrument reveals the growth patterns encoded in every diamond's internal structure. Natural diamonds show irregular octahedral patterns reflecting geological complexity. HPHT diamonds show cross-shaped cuboctahedral sector patterns from controlled press growth. CVD diamonds show parallel banding from layer-by-layer plasma deposition. These patterns are highly distinctive, visually intuitive, and among the most definitive identification tools in gemology — providing a growth-method fingerprint that complements spectroscopic analysis and is difficult to misinterpret.