How to identify real Nephrites vs lab-grown ones: Expert identification guide

Nephrite is one of the two true jades (the other is jadeite). It’s prized because it’s tough, wearable, and quietly beautiful. But the market is crowded with imitations, dyed stones, polymer-filled pieces, and reconstituted “jade.” This guide shows how to tell natural nephrite from lab-made or man‑made lookalikes using clear, practical tests. You’ll see what to check first with your eyes and hands, what to do with basic instruments, and when to rely on a lab.

What “real nephrite” means—and what “lab‑grown” usually is

Real nephrite is a massive, interlocking aggregate of amphibole minerals (tremolite–actinolite). Its felted, tough microstructure is the key to its identity and durability.

Lab‑grown nephrite is not made commercially like synthetic sapphires or diamonds. When sellers say “lab-grown,” they usually mean one of these:

• Reconstituted/pressed material: nephrite powder mixed with resin, then molded. It’s man‑made and not equivalent to natural stone.
• Polymer‑impregnated stone: porous or fractured nephrite stabilized with polymers. It’s altered and should be disclosed.
• Imitations: glass, serpentine (including bowenite), dyed quartzite, prehnite, hydrogrossular, calcite, or plastic.

Understanding this matters because each behaves differently under tests. Natural nephrite has a fibrous, interlocking texture that imitations cannot duplicate.

Quick triage: what you can do in minutes

• Weight and feel: Nephrite has a specific gravity around 2.90–3.10, so small pieces feel a bit heavy for their size. Plastics feel light; serpentine and glass often feel slightly lighter. Natural stone stays cool in the hand longer than resin because stone conducts heat away from your skin more slowly.
• Surface and polish: Under bright light, well‑polished nephrite often shows a subtle “orange-peel” texture because the felted fibers wear microscopically unevenly. Glass polishes to a wet, flat shine with no texture. Quartzite shows sugary sparkles from grains.
• Color and pattern: Nephrite colors run from creamy white to gray‑green to darker greens and black. Color is typically slightly uneven with soft, cloudlike areas. Neon or “Jolly Rancher” green suggests dye or glass. Look for concentrations of color along fractures; dye pools there.
• Translucency: Hold a flashlight at the edge. Nephrite often shows a warm, even glow through the margin. Glass can look too clean and uniform; quartzite shows granular outlines; serpentine may look waxy and patchy.
• Sound: Lightly tap two pieces together. Nephrite has a crisp, bell‑like clink because of its toughness and elasticity. Glass and plastic sound dull. This is supportive, not decisive.

Microscope clues: texture tells the truth

A 10–40× loupe or microscope is the best low‑cost detector. You’re looking for nephrite’s characteristic felted microstructure.

• Felted, fibrous aggregate: Natural nephrite shows a matted tangle of extremely fine fibers, often best seen at edges, tiny chips, or near drill holes. This interlocking texture is why nephrite is so tough.
• Splintery fracture: Chips show splintery edges, not conchoidal scallops. Glass shows smooth, curved (conchoidal) fractures. Quartzite shows granular breaks.
• Dye concentrations: In treated stones, you’ll see stronger color along fissures and grain boundaries, sometimes with a fuzzy “halo.” Untreated nephrite has more diffuse color.
• Bubbles and swirls: Spherical bubbles or flow lines indicate glass. Flat, plate‑like textures point to serpentine rather than nephrite.
• Resin “skin” or pits with plastic luster: Reconstituted material and polymer‑rich surfaces show a plasticlike shine in pits and carvings; you may see particulate grains suspended in a resin matrix.

Simple instrument tests most buyers can do

• Refractive Index (RI): Spot RI on a refractometer typically reads about 1.60–1.62 for nephrite (commonly ~1.61). Glass is usually ~1.50–1.52; quartzite ~1.54–1.55; serpentine ~1.56–1.57. This matters because RI reflects how light slows in the material; different structures bend light differently.
• Specific Gravity (SG): Hydrostatic SG for nephrite is ~2.90–3.10. Serpentine is lower (~2.55–2.65). Glass varies (~2.40–2.60). SG narrows the field because density is tied to composition.
• UV fluorescence: Natural nephrite is usually inert to longwave and shortwave UV. Polymer impregnation often gives a patchy blue‑white glow. Some dyes fluoresce unevenly. Inertness supports natural, but glowing alone doesn’t prove treatment; some resins are non‑reactive.
• Hardness check (careful): Nephrite is ~6–6.5 on Mohs. It can mark common glass (~5.5) but is easily scratched by quartz (7). Avoid destructive scratch tests on finished pieces; use this only on rough or inconspicuous spots.

Advanced lab methods (when certainty matters)

• Raman spectroscopy: Identifies the tremolite–actinolite signature bands instantly. It distinguishes nephrite from serpentine, quartzite, glass, and polymers because each has different lattice vibrations.
• FTIR spectroscopy: Confirms amphibole OH-stretch features and detects polymers via C–H and carbonyl peaks. It’s the go‑to for spotting impregnation even when UV is silent.
• XRD (X‑ray diffraction): Definitive for crystalline phase identification (amphibole vs serpentine vs quartz). Used when the piece is unusual or high value.
• SEM/EDS: Microscopy and elemental analysis can show fibrous textures and chemistry (Mg/Fe/Ca ratios) and reveal resin present in pores.

Color and treatment patterns you’ll actually see

• Dyed green nephrite: Often too bright. Under the scope, color concentrates in cracks and along grain edges. UV may show patchy fluorescence from dye carriers.
• Bleach + polymer (stabilized): Surface looks extra glossy and “wet.” UV often glows; FTIR confirms polymers. The why: bleaching opens pores; polymer adds clarity and strength but must be disclosed.
• Reconstituted “nephrite”: Uniform color, low weight relative to size, and a resinous luster in recesses. Under magnification, you’ll see grains in a binder instead of a continuous felted fabric.

Common impostors and how to spot each

• Serpentine (including bowenite): Softer, lower SG, often more waxy. RI ~1.56–1.57. Microscopy shows platy or micro‑fibrous textures, not the dense felt of nephrite.
• Quartzite (“dushan jade”/dyed quartzite): Granular sparkle under magnification. RI ~1.54–1.55; SG ~2.65. Takes dye vividly.
• Glass: Conchoidal fractures, round bubbles, swirled flow lines, uniform color. RI ~1.50–1.52; SG often <2.60.
• Prehnite/hydrogrossular: Often shows botryoidal or granular structures. Different RIs and SGs; Raman separates quickly.
• Plastic/resin: Very light, warms fast, dull thud on tap. Under a hot needle, it smells and melts—but avoid this destructive test on any suspect valuable item.

Red flags when buying

• Overly vivid greens at low prices.
• Perfectly uniform color with no zoning or mottling in carved pieces.
• High‑gloss, glassy luster without the subtle orange‑peel texture.
• “Lab-grown nephrite” claims: Treat as man‑made or reconstituted unless a reputable lab says otherwise.
• No disclosure about treatments on mass‑market carvings and beads—assume some are dyed or stabilized.

A practical workflow you can follow

• 1) Visual triage: Check color, translucency, and polish texture. Look for dye concentrations and glasslike fractures.
• 2) Weight and sound: Gauge heft and tap for tone. Light and dull suggests resin or plastic.
• 3) Magnification: Hunt for felted fibers versus bubbles, grains, or resin matrix.
• 4) Instrument checks: Measure RI (~1.61 supports nephrite) and SG (~2.90–3.10). Try UV for polymer clues.
• 5) When value is high or results conflict: Get Raman/FTIR from a competent gem lab.

Why these tests work

• Texture drives identity: Nephrite’s interlocked fibers resist chipping and create splintery fractures and orange‑peel polish. Imitations lack this microstructure.
• Optical constants are composition‑bound: RI and SG reflect the mineral’s chemistry and structure; they cluster in ranges that separate amphiboles from glass, quartz, and serpentine.
• Spectroscopy “hears” the lattice: Raman and FTIR detect specific bond vibrations. Polymers and dyes leave their own unmistakable signatures.

Care and handling (especially for treated pieces)

• Avoid harsh cleaners, ultrasonics, and steam: They can leach dye or damage polymer fills.
• Wipe with a soft damp cloth: Mild soap only if needed; dry well.
• Store separately: Nephrite is tough but can scratch softer stones and metals can mar its polish.

Myths to ignore

• “If it rings when tapped, it’s real.” Helpful but not definitive; some glass rings, some nephrite won’t if the piece is damped by settings.
• “Scratch it with steel.” Steel is too soft to be conclusive and scratching devalues pieces.
• “Bubbles mean fake, no bubbles mean real.” Bubbles prove glass, but many fakes aren’t glass.
• “UV tells all.” Many resins don’t fluoresce; some natural stones can show weak reactions.

Bottom line

Natural nephrite announces itself with density, a calm and slightly mottled color, a crisp clink, and—most importantly—a felted, fibrous texture under magnification. Most “lab‑grown” offers are reconstituted or polymer‑stabilized products, or entirely different stones. Use RI and SG to narrow it down, microscope work to confirm the texture, and spectroscopy for expensive or ambiguous cases. If a deal looks too bright, too uniform, or too cheap, slow down. Real nephrite rewards patience—and careful testing.