Lab-Grown Diamonds, Moissanite and Cubic Zirconia: Differences and Comparison
Updated: Oct 27
Lab-grown diamonds, moissanite and stones marketed as “high-carbon diamonds” can all have a colourless, transparent and sparkling appearance. Their material identities are fundamentally different: a lab-grown diamond is a genuine diamond; moissanite is silicon carbide; and “high-carbon diamond” is a commercial name commonly used for cubic zirconia (CZ). Moissanite and CZ are diamond simulants.
For people who want to wear their jewellery for years and enjoy the appearance of diamond, lab-grown diamonds offer diamond’s own optical properties and scratch resistance at a more accessible price. Moissanite is known for strong fire and good hardness, while CZ offers low-cost decorative possibilities. Comparing their origin, rarity, sparkle, hardness, colour, clarity, price and resale prospects gives a more useful picture than appearance alone.
Figure 1. All three materials can have a colourless, faceted appearance. AI illustration.
Contents
1 Material Identity and Origin
“Lab-grown” describes the production origin; “diamond” identifies the material. A lab-grown diamond consists of carbon atoms arranged in the diamond crystal structure and has essentially the same chemical, physical and optical properties as a natural diamond. Moissanite and CZ are different materials, each with its own properties even when manufactured in a controlled environment. [1][7]
Scores in the comparison tables are RAGAZZA’s editorial assessments for jewellery use, from 1 to 5, with 5 highest. They are not laboratory grades. Colour and clarity scores refer to good-quality colourless examples; affordability refers to general loose-stone pricing; and the value-retention score is a recommendation about suitability as a store of value, rather than a resale forecast.
Figure 2. Nine-attribute radar profiles for lab-grown diamond, moissanite and high-carbon diamond (CZ), using the scores in the comparison tables. Click the image to enlarge.
Comparison | Lab-Grown Diamond | Moissanite | High-Carbon Diamond (CZ) |
|---|---|---|---|
Principal composition | Carbon (C) | Silicon carbide (SiC) | Zirconium dioxide (ZrO₂) with stabilisers |
Material identity | Diamond of lab-grown origin | Silicon carbide gemstone; not diamond | Manufactured cubic zirconia; not diamond |
Source for jewellery | Grown diamond crystals | Mainly lab-created; natural moissanite is extremely uncommon | Manufactured crystals suitable for cutting |
Common production method | HPHT or chemical vapour deposition (CVD) | High-temperature silicon-carbide single-crystal growth | Melting zirconia with stabilisers, followed by crystallisation |
Relationship to natural diamond | Same material; different growth origin | Similar appearance from a different material | Similar appearance from a different material |
Diamond material score | 5/5 | 1/5 | 1/5 |
“High-Carbon Diamond” Is a Commercial Name for CZ
In the general jewellery market, “high-carbon diamond” normally means cubic zirconia (CZ). The name does not give it diamond’s carbon crystal structure. CZ is also different from natural zircon, whose principal composition is zirconium silicate. Throughout this comparison, high-carbon diamond means CZ. [4][14]
These are only three of the materials available among manufactured gems. Ruby, sapphire and emerald also have lab-grown counterparts; explore our complete guide to lab-grown gemstones.
2 Rarity and Supply
Rarity must be understood together with origin and quality. Natural moissanite is exceptionally uncommon, but the lab-created moissanite sold in jewellery is not priced on that natural rarity. Lab-grown diamond production likewise does not depend on finding a natural diamond deposit. Scalable production still does not mean that every growth run produces the same size, colour and transparency. [3][11]
Comparison | Lab-Grown Diamond | Moissanite | High-Carbon Diamond (CZ) |
|---|---|---|---|
Dependence on natural deposits | No natural diamond mine required | Mainstream jewellery material does not depend on natural moissanite deposits | No natural gem-quality CZ deposit required |
General supply | Industrial production, sorted by size and quality | Established lab-created jewellery supply | Mature mass-produced decorative material |
Individual quality differences | Large sizes, high colour, clarity and good cut still require selection | Colourlessness, size, cut and surface quality vary | Colour, size, cut and polish vary |
Purchasing focus | Material identity and individual quality | Preferred fire and finished quality | Design, budget and workmanship |
Natural-origin rarity score | 1/5 | 1/5 | 1/5 |
For everyday jewellery, a dependable supply also helps with matching stones and finding replacements. Whether an individual stone deserves to be used still depends on its quality. Controlled production creates opportunities; it does not replace selection.
3 Sparkle and Lustre
Jewellery sparkle includes brightness from white light, fire as light separates into spectral colours, and the flashes of light and dark seen as a stone moves. Lustre describes light reflected from the surface. All three materials can look bright; their differences arise from how the material handles light and how well the cut brings those properties out.
Comparison | Lab-Grown Diamond | Moissanite | High-Carbon Diamond (CZ) |
|---|---|---|---|
Refractive index | Approx. 2.42 | Approx. 2.65–2.69 | Approx. 2.15–2.18 |
Dispersion | Approx. 0.044 | Approx. 0.104 | Approx. 0.058–0.066 |
Fire under point light | Coloured flashes characteristic of diamond | Usually stronger, vivid coloured flashes | Coloured flashes with a different appearance from diamond |
Rear-facet appearance | Single refraction; no birefringent doubling | Common gem-quality material is doubly refractive; suitable viewing directions show doubling | Single refraction; no birefringent doubling |
Lustre and facets | Diamond lustre; good cutting gives sharp facets and contrast | Bright lustre; birefringence and cutting orientation affect facet images | Can take a bright polish; cut and surface condition affect appearance |
Diamond optical character score | 5/5 | 3/5 | 2/5 |
Coloured-fire intensity score | 3/5 | 5/5 | 4/5 |
Stronger Fire and a More Diamond-Like Appearance Are Different Qualities
Moissanite’s higher dispersion can produce particularly vivid rainbow flashes under suitable point lighting. Some people enjoy that effect. A lab-grown diamond has diamond’s refractive and dispersive properties, producing the same type of optical behaviour as a natural diamond. Wanting the appearance of diamond itself is a direct reason to choose a lab-grown diamond. [1][3]
Figure 3. Single and double refraction shown through rear-facet edges. Optical concept diagram.
The visibility of doubling in moissanite depends on viewing direction and cutting orientation. A stone that looks sharp face-up may show doubling when tilted. Single refraction alone does not guarantee brightness: poor proportions or polish can compromise the light performance of diamond or CZ too. [3][4]
Compare Clean Stones of Similar Size Under the Same Lighting
Slowly rotate three clean stones of similar size under the same light. Look at brightness and transparency in soft light, then fire under point lighting. This makes personal preferences easier to recognise. Lighting changes the appearance of all three, and dramatic flashes in a video are affected by filming conditions. For more detail, read how cutting style, cut quality and clarity affect diamond sparkle.
Figure 4. Diamond sparkle under soft and point lighting. AI lighting illustration.
4 Hardness and Durability
For a stone worn on the hand every day, retaining a good polish matters beyond its initial sparkle. Mohs hardness describes resistance to scratching. Durability also includes resistance to chipping and stability under heat, chemicals and other environmental conditions. [6]
Comparison | Lab-Grown Diamond | Moissanite | High-Carbon Diamond (CZ) |
|---|---|---|---|
Mohs hardness | 10 | Approx. 9.25 | Approx. 8–8.5 |
Relative scratch resistance | Highest; best resistance to surface abrasion | Very high, but below diamond | Lower; wear can accumulate more readily |
Impact and chipping | Has cleavage; strong impacts and vulnerable edges can chip | Good toughness; protect edges and settings | Can chip; protect exposed edges |
Long-term appearance | Oil, dirt, chips and prong condition | Oil, dirt and surface damage | Oil, dirt and wear at facets and edges |
Frequently worn rings | For diamond sparkle and long-term scratch resistance | For strong fire and high hardness | For low-budget styling with lower scratch resistance |
Scratch-resistance score | 5/5 | 4/5 | 3/5 |
Mohs Hardness Is Not a Percentage Scale
A Mohs value of 9.25 does not mean 92.5% of diamond’s scratch resistance, and the intervals on the scale are not equal. Diamond is the most scratch-resistant of these three materials, but the hardest material is not automatically the most impact-resistant. Girdle thickness, prong placement and protection from the setting also matter, especially for pointed or angular stones. [6]
Cleaning Removes Dirt; It Does Not Repair Wear
Oil films and soap deposits can reduce sparkle, which suitable cleaning may restore. Scratches, chips and worn facets require a professional assessment for repair or replacement. Cleaning should suit the jewellery’s metal, setting and any gemstone treatments, and the material should be disclosed before repairs.
Figure 5. A clean surface, surface oil film and facet wear. AI enlarged illustration.
5 Colour
A colourless appearance is not exclusive to lab-grown diamond: moissanite and CZ can also appear colourless or near-colourless. Compare the actual stones as well as their descriptions, looking for unwanted tints under soft white light and checking whether the appearance is even throughout. [5][9]
Comparison | Lab-Grown Diamond | Moissanite | High-Carbon Diamond (CZ) |
|---|---|---|---|
Colourless products | Available in colourless and near-colourless grades | Colourless and near-colourless products available | Can be manufactured colourless |
Coloured products | Coloured lab-grown diamonds; check colour and treatment information | Yellow, blue, green and other colours | Can be manufactured in many colours |
Reading colour labels | Diamond grading on reports such as IGI; read the issuing laboratory’s system | May use labels such as D colour; check the assessment standard | Check the meaning of colour names or D-colour labels |
Inspecting a colourless stone | Look for unwanted brown, grey, green or blue tints and assess transparency | Inspect yellow, grey or other tints face-up and when tilted | Check chosen colour, evenness and surface condition |
Colourless appearance of good examples | 5/5 | 5/5 | 5/5 |
An IGI lab-grown diamond report provides a defined colour grading scale for reference. The same letters on moissanite or CZ must be understood within that material’s own assessment system. Two stones that both look colourless may still look different because of their optics, cut and underlying tint. [9]
The same principle applies to coloured stones. To obtain the material and optical properties of a coloured diamond, confirm that the product is a lab-grown coloured diamond. Similar pink or blue colour names and photographs alone do not identify a gemstone’s material.
6 Clarity and Transparency
Clarity describes inclusions and surface features. Transparency, as seen in person, is the overall impression of how clear a stone looks. A controlled growth environment can still produce inclusions; individual stones in all three materials require selection. [5][10]
Comparison | Lab-Grown Diamond | Moissanite | High-Carbon Diamond (CZ) |
|---|---|---|---|
Can it be eye-clean? | Yes, depending on clarity and inclusion placement | Yes; good examples can look clear | Yes; good examples commonly look clean |
Possible internal features | Metallic inclusions, non-diamond carbon and other growth features | Needle-like or other growth inclusions | Particles, bubbles or growth features |
Clarity information | Reports such as IGI can list IF, VVS, VS and other diamond grades | Check who assessed any stated clarity and how | Check who assessed any stated clarity and how |
Reasons for an unclear appearance | Inclusions, haze, cut or surface dirt | Inclusions, dirt or doubled facet edges | Inclusions, dirt or surface wear |
What to check | Report, magnified inspection and transparency at normal distance | Assess inclusions separately from doubling | Assess inclusions separately from surface wear |
Eye-clean appearance of good examples | 5/5 | 5/5 | 5/5 |
For example, HPHT lab-grown diamonds can contain metallic inclusions, while CVD diamonds may contain non-diamond carbon and other growth features. Their number, size and position affect quality. High clarity is a result of selection, not something every lab-grown diamond automatically possesses. [10]
Rear-facet doubling in moissanite is an optical effect, separate from inclusions. An internally clean moissanite may still show doubling from a suitable direction. When we select diamonds, we assess actual transparency as well as grades and exclude stones with unacceptable milkiness or haze. [3][12]
7 Size and Price
Price comparisons start with the same apparent size and the same scope of quotation. Carat is a measure of weight: 1 ct equals 0.2 grams. Because these materials have different densities, stones of identical volume do not have identical weights.
Comparison | Lab-Grown Diamond | Moissanite | High-Carbon Diamond (CZ) |
|---|---|---|---|
Specific gravity | Approx. 3.52 | Approx. 3.22 | Approx. 5.6–6.0 |
Identical volume and proportions | 1.00 ct reference | Approx. 0.91 ct | Approx. 1.59–1.70 ct |
Comparing visible size | Use millimetres, shape and depth proportions | Use millimetres; distinguish actual weight from diamond-equivalent size | Use millimetres; distinguish actual weight from diamond-equivalent size |
Figure 6. Weight calculated from specific gravity at identical volume and cutting proportions.
“1 carat diamond-equivalent size” or Diamond Equivalent Weight (DEW) can describe appearance relative to a diamond rather than the material’s actual weight. Before comparing loose-stone prices, check measurements in millimetres so that the stones are genuinely comparable in size.
Price and Budget Uses Side by Side
Comparison | Lab-Grown Diamond | Moissanite | High-Carbon Diamond (CZ) |
|---|---|---|---|
General price position | Genuine diamond material, usually more accessible than comparable natural diamond | Generally lower stone budget for high hardness and vivid fire | Usually the lowest stone budget for decoration and styling |
Main pricing factors | Carat, shape, colour, clarity, cut, report and supply | Size, colour, cut, brand and jewellery configuration | Size, cut, polish, quantity and jewellery configuration |
Material qualities purchased | Diamond optics and high scratch resistance | Silicon carbide’s fire and hardness | CZ’s appearance and decorative use |
Complete jewellery quotation | Include setting metal, workmanship, accents and service | Include setting metal, workmanship, accents and service | Include setting metal, workmanship, accents and service |
General affordability score | 3/5 | 4/5 | 5/5 |
These are general product positions rather than fixed price multiples. Complete jewellery from different brands can overlap in price because of stone quality and metal configuration. Lab-grown diamond retail prices are already accessible enough to include in a budget comparison before deciding whether a different material is needed for a similar appearance.
In our price guide published on 9 October 2026, a 1.00–1.09 ct round, D-colour lab-grown loose diamond with at least VVS2 clarity, an IGI report and 3EX had an indicative price of HK$2,500–3,329, approximately NT$10,000–13,316. The Taiwan-dollar figures use the guide’s budgeting conversion of HK$1 to approximately NT$4; they are not a live exchange rate or a formal Taipei showroom quotation. Check individual stones on our diamond selection page, or consult the lab-grown diamond price guide for other sizes. [8]
When comparing a complete ring, include both the centre stone and setting. At RAGAZZA, the complete ring price is the centre-diamond price plus the setting price. The setting price includes that design’s metal, setting work, production, accent stones and service. Quotation formats vary among brands, so check what is included to compare the materials and finish of the whole piece. [8]
8 Value Retention and Resale
Value retention, the ability to resell, and jewellery that continues to look good are different questions. The first two require a real buyer and workable transaction terms; the third depends on materials, craftsmanship and condition. For these three generally manufactured centre-stone materials, we recommend choosing first for wear and an acceptable budget, and obtaining a separate actual offer if resale is required.
Table 9. How to assess resale
Comparison | Lab-Grown Diamond | Moissanite | High-Carbon Diamond (CZ) |
|---|---|---|---|
Material identity on resale | Disclose lab-grown diamond origin | Trade as silicon-carbide gemstone or complete jewellery | Trade as CZ or complete jewellery |
Centre-stone valuation | Buyer demand, current comparable new-stone prices and individual quality | Buyer acceptance, replacement cost and condition | Replacement cost, buyer acceptance and the whole piece |
Original-price recovery or appreciation | Purchase itself makes no such promise | Purchase itself makes no such promise | Purchase itself makes no such promise |
Metal and brand | Assess metal, brand and craftsmanship separately | Assess metal, brand and craftsmanship separately | Assess metal, brand and craftsmanship separately |
Practical purchasing value | Diamond material and long-term wear within budget | Preferred fire and wear within budget | Decoration and design at a lower budget |
Recommendation as a store of value | 1/5 | 1/5 | 1/5 |
A lab-grown diamond has diamond’s material identity, but resale buyers still distinguish its origin from natural diamond. New supply and the current price of comparable new stones also affect second-hand demand. Moissanite and CZ trade within their own material and jewellery markets, rather than at natural-diamond resale prices.
For an 18K gold ring set with CZ, the gold and centre stone need separate valuations; the same applies to moissanite or lab-grown diamond rings. Buy-back, trade-in and upgrade arrangements follow their written terms, including whether cash is offered, whether credit can only be used for a new purchase, and how the credit is calculated. The table describes assessment factors without assuming a fixed recovery percentage.
9 Identification and Reports
Material identification and quality grading perform different tasks. First establish which gem is being purchased, then understand its colour, clarity, cut and weight. A report should match the stone’s measurements, weight and identifying features, and can be checked with the issuing laboratory. [7][9]
Comparison | Lab-Grown Diamond | Moissanite | High-Carbon Diamond (CZ) |
|---|---|---|---|
Material stated in documents | Laboratory Grown Diamond or a clear equivalent | Moissanite or silicon carbide | Cubic Zirconia or a clear equivalent |
Grading information | Diamond colour and clarity grades, with lab-grown origin disclosed | A quality description is not automatically a diamond grading report | A quality description is not automatically a diamond grading report |
Typical thermal tester | Usually indicates diamond; cannot establish natural versus lab-grown origin | May indicate diamond; thermal testing alone is insufficient | Suitable instruments generally distinguish it from diamond, with correct operation |
Electrical tester limitations | Some instruments may identify certain lab-grown diamonds as moissanite | Offers clues when interpreted within the instrument’s intended use | Does not replace full material identification |
More complete confirmation | Report check, gemmological observation and origin testing as needed | Gemmological observation and suitable material testing | Gemmological observation and suitable material testing |
IGI notes that moissanite may produce a “diamond” result on a thermal-conductivity tester, while some lab-grown diamonds may produce a “moissanite” result on certain electrical testers. A tester’s response must therefore be interpreted within its operating principles and intended use. Professional identification combines observation with suitable equipment instead of relying on a single reaction. [7]
10 Why RAGAZZA Uses Lab-Grown Diamonds
RAGAZZA regards moissanite and high-carbon diamond (CZ) as diamond simulants. We do not use or sell either material, whether as centre stones or accent stones. Both have their own advantages, but for fine diamond jewellery we consider lab-grown diamond’s material identity, optical character and scratch resistance superior overall to these two simulants. We therefore use carefully selected, high-quality lab-grown diamonds.
Table 11. RAGAZZA’s material policy
Comparison | Lab-Grown Diamond | Moissanite | High-Carbon Diamond (CZ) |
|---|---|---|---|
Material classification | Genuine diamond, lab-grown origin | Diamond simulant: silicon carbide | Diamond simulant: cubic zirconia |
Centre stones | Carefully selected, high-quality lab-grown diamonds | Not used | Not used |
Accent stones | Diamond accents meeting our quality requirements | Not used | Not used |
Sold by RAGAZZA | Lab-grown diamond jewellery | Not sold | Not sold |
Reason for our policy | Diamond sparkle with high scratch resistance and refined craftsmanship | Strong fire is an advantage, but the material does not meet our diamond-jewellery standard | Low stone cost is an advantage, but the material does not meet our diamond-jewellery standard |
Figure 7. Examining a gem and checking its documentation with suitable tools. AI process illustration.
After identifying the material, we assess each diamond’s colour, transparency and light performance, excluding unacceptable tints, milkiness and haze. For round brilliant diamonds, our independently developed DAII™ Diamond Quality Index combines 16 data points to support comparison alongside physical inspection. [12][13]
Settings and stone placement are planned around the design and wear, with attention to centre-stone proportions, prongs, finishing and polish. These processes translate the material’s qualities into a finished jewel. Explore RAGAZZA’s 11-point professional selection process for premium lab-grown diamonds.
Figure 8. The centre diamond, diamond accents and metal craftsmanship work together to create a refined jewel. AI craftsmanship illustration.
We choose high-quality lab-grown diamonds and carry the same material standard through the centre stone, accent stones and finished piece. Explore our engagement ring designs or book a showroom appointment, where we can help compare diamond size, quality and a complete jewellery budget.
11 Frequently Asked Questions
Q1. Is a high-carbon diamond a lab-grown diamond?
A. No. High-carbon diamond is a commercial name commonly used for cubic zirconia (CZ), principally zirconium dioxide with stabilisers. A lab-grown diamond is carbon with the diamond crystal structure. They are different materials, and CZ is not a lab-grown diamond.
Q2. Why choose a lab-grown diamond when moissanite has stronger fire?
A. Fire is one part of a stone’s overall light performance. Moissanite produces vivid coloured flashes, while a lab-grown diamond offers diamond’s own combination of brightness, light-and-dark contrast and fire, together with greater scratch resistance. For someone who wants diamond’s optical character, lab-grown diamond directly fulfils that requirement.
Q3. Do the same D-colour and VVS labels mean the same quality?
A. Start with the material and assessment standard. Colour and clarity on diamond reports from laboratories such as IGI are interpreted within the diamond grading system. The same letters on moissanite or CZ still require clarification of the colour and clarity assessment method and do not give those materials diamond’s optical properties.
Q4. Which looks larger at one carat?
A. If each stone genuinely weighs one carat, a lower-density material can occupy more volume. Face-up size also depends on shape and depth. Some products use diamond-equivalent size instead of actual weight, so compare millimetre measurements and proportions for the most direct indication of visible size.
Q5. Does a stone need replacing if it loses its sparkle?
A. Have it examined by a professional first. Suitable cleaning can often remove oil and dirt; scratches, worn facets or chips may require repair or replacement. Scratch resistance, wear habits and the condition of the setting all influence the appropriate response.
Q6. Should I compare the centre stone or the complete piece first?
A. Establish the centre-stone material and desired size, then include quality, metal, setting, accent stones and service in the complete budget. Material comparison helps determine the stone direction; comparing the complete jewel shows its actual finish, suitability for wear and total price.
Sources
Sources consulted on 26 October 2026. Physical values are gemmological reference values. Moissanite figures refer to common gem-quality material; CZ values vary with stabilisers and other conditions. Historical studies are used for material properties, not as estimates of today’s production or the grades of all current products. Price examples state their quotation date and conversion basis.
