Can You Tell the Difference Between a Lab-Grown Tennis Necklace and a Natural One?

Diamond tennis necklaces have become incredibly popular. But can you tell if the one you are going for is lab-grown or mined from the earth? Without a doubt, lab-grown diamonds are continuing to rise in popularity due to their affordability, and many buyers are left stunned by how to differentiate between the two.

Investing in a high-end piece or choosing an ethically sourced option requires understanding the difference to make the right purchase.

More than just brilliance, buyers demand transparency, long-term assurance, and good value. Pricing, resale options, environmental concerns, plus certification, the distinction between lab-grown and natural diamonds has real implications.

Want to learn from the basics? Read this: Lab made diamonds vs mined ones.

In this post, you’ll learn how to spot each type visually, understand what professionals focus on, and discover how those differences influence quality, wear, and price.

A Quick Comparison Between Lab vs Natural Tennis Necklace

Method	How to Use	What to Look For	What to Look For
🔍 Laser Inscription Check	Use a 10x jeweler’s loupe or microscope	Look for "Lab Grown", "LG", or "Synthetic" on the diamond girdle	⭐⭐⭐⭐⭐ (Very High)
💡 UV Light/Phosphorescence	Shine a UV flashlight, turn off, and observe	Lab diamonds (especially CVD) may glow (phosphoresce) after UV is off	⭐⭐⭐⭐ (High)
💰 Price Comparison	Compare the price of the necklace to known market values	Lab-grown diamonds are 30–70% cheaper than natural diamonds for the same size/quality	⭐⭐ (Medium-Low)
👁️ Color/Clarity Consistency	Inspect diamonds with a loupe or a microscope	Lab diamonds are often more uniform in color and clarity	⭐⭐ (Medium-Low)
📄 Certification Check	Ask the seller or check the documents	IGI or GCAL = likely lab-grown; GIA (older) = likely natural	⭐⭐⭐⭐ (High)
🧪 Diamond Tester (Advanced)	Use a thermal/electrical tester or a UV fluorescence tool	Advanced testers may identify lab-grown via conductivity or fluorescence	⭐⭐⭐⭐ (High)

Lab-Grown Tennis Necklace vs Natural Diamond Tennis Necklace: The Basics

The foundation of any tennis necklace, whether lab-grown or natural, is the diamond. While both options offer stunning aesthetics and identical physical properties, the real differences emerge at the atomic, structural, and geological levels. This section dives into those aspects with precision.

1. Composition, Crystal Structure, & Geologically Distinct

Both lab-grown and natural diamonds are crystalline carbon arranged in a face-centered cubic lattice, with a Mohs hardness of 10. However, their formation processes differ drastically:

Natural Diamonds form over 1–3 billion years deep in the Earth’s mantle under extreme conditions and are brought to the surface through kimberlite pipes. These diamonds typically exhibit cubo-octahedral crystal morphology, complex strain patterns, and contain natural inclusions such as olivine or garnet.

Lab-Grown Diamonds are synthesized in laboratories using either High Pressure High Temperature (HPHT) or Chemical Vapor Deposition (CVD):

• HPHT diamonds mimic natural geological processes with metal catalysts and exhibit metallic flux inclusions.
• CVD diamonds grow in carbon plasma environments and often display layered growth striations and are typically Type IIa diamonds (extremely rare in nature).

These formation routes result in unique crystal growth lines, impurity patterns, and morphologies that are identifiable under magnification and spectroscopy.

2. Inclusions, Impurities, and Type Classification

Natural diamonds are predominantly Type Ia, containing aggregated nitrogen impurities that may give them a yellowish tint. Their inclusions, like feathers, clouds, and mineral crystals, are irregular and organic in appearance.

Lab-grown diamonds vary

• HPHT diamonds are often Type Ib, with isolated nitrogen atoms, and may fluoresce yellow, green, or orange due to metallic catalysts.
• CVD diamonds are commonly Type IIa, with minimal nitrogen, and show distinct strain birefringence and graphitic inclusions.

These nitrogen-based classifications are confirmed using infrared spectroscopy, UV-Vis spectroscopy, and photoluminescence imaging, all standard in gemological labs.

3. Optical & Fluorescence Behavior, Visual Features Under Magnification

To the unaided eye, both types of diamonds are virtually identical. But under magnification (10x loupe or microscope), experts look for:

Natural diamonds: Random inclusion distribution, organic feathering, natural mineral crystals, and diffuse strain patterns.

Lab-grown diamonds show the presence of metallic inclusions, occasionally magnetic, while CVD shows parallel growth lines, visible strain birefringence, and orange-red phosphorescence after UV exposure.

Using tools like DiamondView™, experts can observe growth zoning and post-UV phosphorescent behavior, which is a telltale identifier of lab origin. These diamonds may also exhibit unnatural fluorescence colors or grain patterns unique to their growth method.

4. Laboratory Detection, Certification, and Grading

In 2025, GIA and IGI will offer full certification for both lab-grown and natural diamonds. Lab reports include:

• Laser inscription for traceability.
• Full 4Cs grading: Cut, Color, Clarity, Carat weight.
• Type classification (e.g., Type IIa or Type Ib).
• Spectroscopic and imaging analysis details.

Gem labs use equipment such as FTIR, photoluminescence spectroscopy, DiamondView™ imaging, X-ray topography, and magnetometry to detect:

• Nitrogen/bore impurity levels
• Strain patterns
• Fluorescence/phosphorescence behavior
• Inclusion type and arrangement

These methods not only authenticate the origin but also impact valuation, insurance classification, and investment potential, crucial for anyone considering a diamond tennis necklace purchase.

Visual Identification: What You Can See

Despite their visual similarity, lab-grown and natural diamond tennis necklaces exhibit subtle, technical differences that trained professionals can detect through careful observation and magnification. Here's a focused breakdown:

1. Naked Eye Clues: Brilliance, Color & Cut Uniformity

To the unaided eye, both types exhibit high brilliance and fire due to identical refractive indices (2.42) and dispersion values (~0.044). However:

• Lab-grown diamonds, especially CVD stones, may show overly perfect uniformity in brilliance and color due to factory-controlled growth.
• Natural diamonds often display slight variation in hue or sparkle, offering a more organic visual character.
• Lab-grown stones are usually cut with CNC precision, resulting in exceptionally consistent facet symmetry compared to slightly varied hand-finished cuts on natural stones.

2. Loupe & UV Light Inspection: Inclusions, Growth, and Fluorescence

Under 10x magnification or a microscope, professionals identify:

Inclusions

• Natural: Feathers, clouds, and mineral crystals, randomly arranged.
• Lab-grown (HPHT): Metallic flux spots; (CVD): Needle-like or striated inclusions.

Growth patterns

• Natural: Cubo-octahedral zoning, organic strain.
• Lab-grown: Parallel striations (CVD), geometric zoning (HPHT).

Fluorescence behavior

• Natural: Soft blue or none.
• Lab-grown: Stronger, uniform; CVD may phosphoresce orange-red after UV exposure.

3. Girdle & Setting Observations: Inscriptions and Craftsmanship

• Laser Inscriptions: Lab-grown diamonds often have girdle markings like “LABGROWN” or lab report numbers, visible under magnification.
• Girdle polish: Typically smoother and more uniform in lab-grown stones due to machine cutting.
• Craftsmanship clues: Lab-grown tennis necklaces tend to feature highly uniform stones and occasionally non-traditional or hallmark-marked settings.

Professional Identification Methods - What Jewelers Look For

When visual cues aren't enough, jewelers and gemologists turn to specialized techniques and instruments to definitively distinguish lab-grown from natural diamond tennis necklaces. These methods rely on identifying growth characteristics, chemical signatures, and microscopic details.

1. Laser Inscription and Certification Analysis

Most lab-grown diamonds come with laser-inscribed identifiers on the girdle, such as:

• "LABGROWN," "LG," or "SYNTHETIC"
• Certification numbers tied to grading labs like GIA, IGI, GCAL, or HRD

Natural diamonds may also carry inscriptions, but without any synthetic identifiers. Jewelers use microscopes with darkfield illumination to locate and verify these inscriptions, cross-referencing them with a certificate for origin, carat weight, and cut details.

2. UV Fluorescence & Phosphorescence Testing

Using long-wave UV light, jewelers observe how diamonds fluoresce:

• Natural diamonds usually fluoresce blue (due to N3 nitrogen centers), if at all.
• HPHT-grown diamonds can fluoresce yellow-green, while CVD-grown diamonds might show orange to red phosphorescence, visible after the UV source is removed.

These patterns are reliable indicators of synthetic origin when interpreted by professionals.

3. Advanced Spectroscopy and Imaging Tools

Gemological labs and expert jewelers utilize instruments to detect growth features and trace elements:

• DiamondView (GIA): Uses short-wave UV imaging to reveal crystal growth structures. CVD diamonds exhibit layered striations, HPHT diamonds show cross-hatched growth, while natural diamonds show octahedral patterns.
• FTIR (Fourier-Transform Infrared Spectroscopy): Identifies the diamond type (Ia, Ib, IIa, IIb). Most CVD diamonds are Type IIa, lacking nitrogen, while natural diamonds are typically Type Ia, containing clustered nitrogen atoms.
• Photoluminescence Spectroscopy: Detects vacancy defects and trace metals, common in HPHT-grown diamonds.

4. Magnetism and Thermal Conductivity Tests

Some HPHT diamonds retain trace metal catalysts (like iron or nickel) from the growth process, making them weakly magnetic, a property not found in natural diamonds. Jewelers may use rare-earth magnets to test for subtle attraction.

Additionally, thermal conductivity testers can now differentiate synthetic stones by evaluating heat dissipation, although this method alone is not conclusive.

Resale Value and Investment Potential, Price Comparison - Lab-Grown & Natural Tennis Necklaces 

As diamond technology advances and market preferences shift, the financial dynamics of tennis necklaces are evolving. Whether you're seeking long-term value or a savvy luxury purchase, understanding the cost and investment breakdown is key.

1. Price Comparison (2025)

In today’s market, lab-grown tennis necklaces are 30–70% less expensive than natural ones of similar cut, clarity, and carat weight. This is primarily due to differences in rarity and supply chain costs.

For better knowledge, read the recent price update of lab-grown diamonds 2025.

This affordability stems from the controlled synthesis process, which bypasses the complexities of mining, transportation, and rarity premiums associated with natural diamonds.

• For buyers wanting a full tennis necklace with multiple stones, lab-grown diamonds allow for larger total carat weight or higher clarity/color grades within the same budget.
• This cost efficiency enables consumers to enjoy the same optical brilliance, cutting precision, and modern craftsmanship at a fraction of the price of natural diamonds.

🔍 Key Technical Insight: Natural diamond tennis necklaces are constrained by geological rarity. Lab-grown tennis necklaces can be replicated at scale with high optical and physical quality, decreasing their scarcity and long-term market value.

2. Resale and Buyback Market Performance

Historically, natural diamonds have commanded stronger resale values due to their rarity and market demand. However, the lab-grown diamond resale market is evolving quickly:

• With increasing consumer acceptance and advancements in certification standards, lab-grown tennis necklaces are gaining traction in resale channels.
• Jewelers and secondary markets now offer competitive buyback programs for certified lab-grown pieces, especially for well-maintained tennis necklaces.
• The resale value for lab-grown diamonds remains stable when sold with proper certification and intact setting quality, making them a practical investment for style-conscious buyers.

3. Investment Potential and Long-Term Value

Lab-grown diamonds appeal beyond traditional investment returns:

• They offer ethical assurance with conflict-free sourcing and a significantly smaller carbon footprint compared to mined diamonds, aligning with sustainable luxury trends.
• Buyers prioritizing responsible consumption find lab-grown tennis necklaces to be an investment in both fashion and future-forward values.
• This growing demand enhances their long-term desirability and potential value retention as consumer awareness rises.

4. Insurance and Appraisal Differences

Insurance companies recognize the lower replacement cost of lab-grown tennis necklaces, often leading to reduced premiums without compromising coverage.

Valuation reports for lab-grown pieces detail the carat weight, cut quality, and certification to accurately assess worth.

Natural diamond tennis necklaces may command higher valuations but come with correspondingly higher premiums, reflecting their rarity and traditional prestige.

🧠 Pro Tip: Always ensure GIA or IGI certification for any tennis necklace, lab-grown or natural, to protect value, verify authenticity, and streamline resale or insurance processes.

5. Customization and Value: Lab-Grown vs Natural Diamond Tennis Necklace

Lab-grown diamonds tennis necklaces offer greater consistency in size for your daily wear and shape, making them ideal for precise customization in tennis necklaces without compromising quality.

Their affordability allows for larger or higher-grade stones within a set budget, enhancing overall value. Natural diamonds tennis necklaces provide unique characteristics that appeal to those valuing rarity and individuality, but may limit uniform customization due to natural variations. Ultimately, lab-grown diamonds deliver superior customization flexibility paired with excellent value.

Can You Really Tell the Difference?

Lab-grown or a natural diamond tennis necklace, it ultimately comes down to personal preference, values, and budget. Lab-grown diamonds offer excellent clarity, uniformity, and affordability, making them ideal for buyers seeking luxury at a lower price with ethical and environmental appeal.

Natural diamond tennis necklaces, on the other hand, hold a timeless resale and heirloom value, appreciated for their unique, earth-formed characteristics.

So, before buying, consider what is most important to you: cost, long-term value, or sustainability.