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Gemstone optimization methods and typical characteristics, Identification characteristics of Natural and Synthetic Gemstones

Unlock the secrets of gemstone treatments with our guide. Learn how to spot enhancements like laser drilling and filling in diamonds, heat treatments in rubies, and dyes in sapphires. Essential for jewelers, designers, and retailers to ensure quality and authenticity in custom-made jewelry.

Gemstone optimization methods and typical characteristics

Identification Characteristics of Common Natural and Synthetic Gemstones

Introduction:

Explore the definitive resource for jewelry aficionados and professionals alike. Dive into the world of gemstone enhancement with detailed methods and characteristics for diamonds, rubies, sapphires, and other precious stones. Learn to distinguish natural gems through their unique identification features, including color, chemical composition, and hardness. Stay ahead in the market by understanding synthetic gemstones and their production methods. This guide is tailored for jewelry stores, studios, brands, retailers, designers, e-commerce sellers, and drop shippers seeking to curate authentic and enhanced gem collections. Enhance your expertise with insights on laser drilling, irradiation, heat treatment, and other optimization processes. Master the nuances of gemstone identification with our comprehensive sections on natural and synthetic characteristics, ensuring you offer only the finest quality to your clientele, including custom-made pieces for celebrities.

Table of Contents

Section I Common gemstone optimization methods and typical characteristics

Jewelry and gemstone names Optimization treatment methods Categories Processing effect Typical identification characteristics
Diamond Laser Drilling Treatment Improve the clarity of diamonds Laser holes can be observed under magnification
Filling Treatment Improve the durability and appearance of diamonds Flashing effect under different fields of view (bright or dark)
Irradiation Treatment Change color Characteristic absorption lines of different colors
Coating Treatment Change in color or appearance Low surface hardness, with scratches and wear
High temperature and high pressure Treatment Improve or change color GE-POL logo or 529nm fluorescence spectrum line and 986nm absorption spectrum line
Ruby Heat treatment Optimization Improve color, remove blue-purple tones The crystalline package has some melting and other heat treatment features
Dyeing treatment Treatment Change or improve color brightness Magnified inspection of the dye distribution along the gemstone's fissures
Filling (colorless oil or wax) Optimization Improving the durability of the gemstone Internal sparkling effect, lower transparency at the fissures
Filling (colored oil or wax) Treatment Improving the color and durability of the gemstone There are internal sparkling effects, and the color distribution along the fissures is magnified.
Diffusion Treatment Improve the color of the gemstone or create a starlight effect Uneven distribution of color inside and outside, with heat treatment characteristics
Jewelry and gemstone names Optimization treatment methods Categories Processing effect Typical identification characteristics
Sapphire Heat treatment Optimization Change or improve appearance Crystalline inclusions have partial melting and other heat treatment characteristics
Dyeing Treatment Improve or change color Magnified inspection of dye distribution along fissures
Filling (colorless wax or oil) Optimization Improve durability, conceal fissures Internal shimmering effect, lower transparency at crack edges
Irradiation Treatment Changing color Color instability, returns to original color after heating
Diffusion Treatment Change color or produce starlight effects Surface diffusion: uneven surface color, lighter internal color; body diffusion: color penetrates into the interior, uniform surface color
Cat's eye Irradiation Treatment Improve color or eyeline Conventional gem testing methods cannot determine
Emerald Filling (colorless oil or wax) Optimization Improve durability There is a sparkling effect internally, and the transparency is lower at the fissures
Filling (colored oil or wax) Treatment Improve gem color and durability Internal sparkling effect, magnified inspection of color distribution along fissures
Dyeing Treatment Change or improve color Magnified inspection of dye distribution along fissures, uneven internal color
Coating Treatment Improve or change color and luster Due to the low hardness of the coated surface, there are scratches on the surface, and magnified inspection can observe that parts of the film often peel off.
Aquamarine Heat treatment Optimization Improve or change color There are some melted inclusions inside.
Dyeing Treatment Improve or change color Magnified inspection shows that the dye is distributed along the fissures, and the internal color is uneven.
Filling (colorless oil or wax) Optimization Improve durability There is a flashing effect inside, and the transparency is lower at the fissures.
Filling (colored oil or wax) Treatment Improve the color and durability of the gemstone Internal sparkling effect, magnifying inspection of color distribution along fissures
Irradiation Treatment Changing color Conventional gem testing methods cannot determine
Beryl Heat treatment Optimization Improve color The heat treatment temperature is relatively low, making it difficult to identify
Filling (colorless oil or wax) Optimization Improve durability There is a flashing effect inside, and the transparency is lower at the fissures
Filling (colored oil or wax) Treatment Improve gem color and durability There is a shimmering effect inside, and the color distribution along the fissures is examined under magnification
Irradiation Treatment Changing color Conventional gem testing methods cannot determine
Coating Treatment Change in color or luster Low surface hardness, often has scratches, wear, and other appearance features
Tourmaline Heat treatment Optimization Improve color There may be some melting in the internal packaging
Filling (colorless oil or wax) Optimization Improve durability There is a sparkling effect inside, and the transparency is lower at the fissures
Filling (colored oil or wax) Treatment Improve gem color and durability Internal glitter effect, magnified inspection of color distribution along fissures
Dyeing Treatment Change the color of the gemstone Magnify and examine the distribution of the dye along the fissures; internal color is uneven
Irradiation Treatment Changing color Good stability; conventional tests cannot determine
Coating Treatment Change in color or luster Low surface hardness, often has scratches, wear, and other appearance features
Zircon Heat treatment Optimization Change or color Low heat treatment temperature, difficult to identify
Irradiation Treatment Changing color Different colors have characteristic absorption lines
Jewelry and gemstone names Optimization treatment methods Categories Processing effect Typical identification characteristics
Spinel Filling (colorless oil or wax) Optimization Improve durability Internal flashing effect, lower transparency at fissures
Filling (colored oil or wax) Treatment Improving the color and durability of gemstones Internal flashing effect, magnified inspection of color distribution along fissures
Dyeing Treatment Change color Uneven color distribution, magnified inspection of color distribution along fissures
Diffusion Treatment Improve or change color The color is limited to the surface, the internal color is light
Topaz Dyeing Treatment Change color The color distribution is uneven, magnify to check the color along the fissures
Diffusion Treatment Change color The color is limited to the surface, the internal color is light, and the external color is dark
Irradiation Treatment Change color Blue topaz is common and has good stability
Coating Treatment Improve color or luster Low surface hardness, with scratches and wear
Garnet Heat treatment Optimization Change or improve color There is partial melting in the internal package.
Filling (colorless oil or wax) Optimization Improve durability There is a flashing effect inside, and the transparency is lower at the fissures.
Filling (colored oil or wax) Treatment Improve the color and durability of the gemstone There are internal flashing effects, and the color distribution along the fissures is magnified.
Crystal Heat treatment Optimization Change or improve color The heat treatment temperature is lower, making it difficult to identify
Irradiation Optimization Changing color Conventional identification instruments cannot distinguish
Filling (colorless oil or wax) Optimization Improve durability There is a flashing effect inside, and the transparency at the fissures is relatively low
Filling (colored oil or wax) Treatment Improve gem color and durability Internal glitter effect, magnified inspection of color distribution along fissures
Dyeing Treatment Change gem color Uneven color distribution, magnified inspection of color distribution along fissures
Coating Treatment Change color, luster, etc. Low surface hardness, with scratches and wear
Feldspar Filling (colorless oil or wax) Optimization Improve durability Internal flashing effect, lower transparency at fissures
Filling (colored oil or wax) Treatment Improve gemstone color and durability Internal flashing effect, magnifying inspection of color distribution along fissures
Coating Treatment Change or improve color and luster Low surface hardness, with scratches, wear, etc.
Diffusion Treatment Changing color Color limited to the surface, light internal color, dark external color
Irradiation Treatment Changing color Color stable, cannot be identified by conventional instruments
Scapolite Irradiation Treatment Changing color Color stable, cannot be identified by conventional instruments
Tanzanite Heat treatment Optimization Changing color Color stable, vibrant blue-purple
Coating Treatment Change color or luster Low surface hardness, with scratches and wear, high content of trace metal elements
Spodumene Irradiation Treatment Changing color Color stable, cannot be identified by conventional instrument
Andalusite Heat treatment Optimization Improve color Color stable, cannot be identified by conventional instruments
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Jewelry and gemstone names Optimization treatment methods Categories Processing effect Typical identification characteristics
Kyanite Dyeing Treatment Change or improve color Uneven color distribution, magnify to check the distribution of the dye along the fissures
Filling (colorless oil or wax) Optimization Improve durability Internal sparkling effect, lower transparency at the fissures
Filling (colored oil or wax) Treatment Improve gem color and durability Internal glitter effect, magnified inspection of color distribution along fissures
Calcite Dyeing Treatment Change or improve color Uneven color distribution, magnified inspection of dye distribution along fissures
Filling (colorless oil or wax) Optimization Improve durability Internal shimmering effect, lower transparency at fissures
Filling (colored oil or wax) Treatment Improve gemstone color and durability There is a flash effect inside, magnifying the inspection of color distribution along the fissures.
Irradiation Treatment Change color Color is stable, cannot be identified by conventional instruments.
Euclase Irradiation Treatment Change color Color is stable, cannot be identified by conventional instruments.
Jade Heat treatment Optimization Improve or change color The color is stable, the coloring principle is the same as that of natural jade, and identification is not necessary.
Filling (colorless oil or wax) Optimization Improve durability There is a flashing effect inside, and the transparency is lower at the fissures.
Filling (colored oil or wax) Treatment Improve gemstone color and durability. There is a flashing effect inside; magnified inspection shows color distribution along the fissures.
Bleaching, filling Treatment Change the color to improve durability. The color is clean and free of impurities, with a flashing effect at the filling
Dyeing Treatment Changing color Uneven color distribution, dye distributed along fissures, colorless roots
Coating Treatment Change in color or luster Low surface hardness, weak luster, with scratches
Nephrite Filling (colorless oil or wax) Optimization Improve durability There are internal sparkling effects, and the transparency is lower at the fissures.
Filling (colored oil or wax) Treatment Improve gemstone color and durability. There are internal sparkling effects, and the color distribution along the fissures is magnified.
Dyeing Treatment Change color The color distribution is uneven, and the dye is distributed along the fissures.
Opal Filling (colorless oil or wax) Optimization Improve durability There is a sparkling effect internally, and the transparency is lower at the fissures
Filling (colored oil or wax) Treatment Improving gemstone color and durability Internal sparkling effect, magnifying inspection of color distribution along fissures
Dyeing Treatment Changing color Common black opal, color distributed along the fissures
Coating Treatment Change in color and luster Surface has scratches and wear, highlighting the play of color
Bonding Treatment Change in color and luster Two-layer stone or three-layer stone, observe the bubbles in the seams and the differences in color and luster of different materials
Chalcedony (Agate) Heat treatment Optimization Improve or change color Color stable, cannot be identified by conventional instruments
Filling (colorless oil or wax) Optimization Improve durability There is a shimmering effect inside, and the transparency is lower at the fissures.
Filling (colored oil or wax) Treatment Improve gemstone color and durability. There is a shimmering effect inside, and the color distribution along the fissures is examined under magnification
Dyeing Optimization Change color The color is vivid, unevenly distributed, and the dye can be seen along the fissures under magnification.
Jewelry and gemstone names Optimization treatment methods Categories Processing effect Typical identification characteristics
Quartzite Jade Dyeing Treatment Change color The color distribution is uneven, and upon magnification, the dye appears to be distributed in a mesh pattern.
Bleaching, filling Treatment Improving color and durability The color is clean and free of impurities, with a sparkling effect in the filled areas
Serpentine Filling (colorless oil or wax) Optimization Improve durability Internal shimmering effect, lower transparency at fissures
Filling (colored oil or wax) Treatment Improve gem color and durability Internal sparkling effect, magnified inspection of color distribution along fissures
Dyeing Optimization Change color Vivid color, uneven distribution, visible dye distribution along fissures under magnification
Turquoise Filling (colorless oil or wax) Optimization Improve durability There are flashing effects inside, and the transparency is lower at the fissures.
Filling (colored oil or wax) Treatment Improve the color and durability of the gemstone. There are flashing effects inside, magnified inspection shows color distribution along the fissures, with color distribution being more obvious at the iron lines.
Dyeing Treatment Change color The color is vivid and unevenly distributed, with visible dye distribution along the fissures upon magnified inspection.
Density optimization Optimization Improve durability and appearance Good stability, no need for identification (should include notes)
Lapis lazuli Filling (colorless oil or wax) Optimization Improve durability Internal flash effect, lower transparency at fissures
Filling (colored oil or wax) Treatment Improving gemstone color and durability Internal sparkling effect, magnifying inspection of color distribution along fissures
Dyeing Treatment Changing color Vivid color, uneven distribution, dye visible along fissures under magnification
Malachite Filling (colorless oil or wax) Optimization Improve durability There is a flashing effect inside, and the transparency is lower at the fissures.
Filling (colored oil or wax) Treatment Improving gemstone color and durability There is a flashing effect inside, and the color distribution along the fissures is examined under magnification.
Marble Filling (colorless oil or wax) Optimization Improve durability There is a flashing effect inside, and the transparency is lower at the fissures.
Filling (colored oil or wax) Treatment Improve gemstone color and durability. Internal sparkling effect, magnifying inspection of color distribution along fissures
Dyeing Treatment Changing color The color is vivid and unevenly distributed; under magnification, the dye can be seen distributed along the fissures.
Coating Treatment Change in color or luster The surface and internal colors are inconsistent, with scratches and wear.
Rhodochrosite Filling (colorless oil or wax) Optimization Improve durability There is a shimmering effect inside, and the transparency is lower at the fissures.
Filling (colored oil or wax) Treatment Improving gemstone color and durability Internal sparkling effect, magnifying inspection of color distribution along fissures
Talc Dyeing Treatment Changing color The color is vivid and unevenly distributed, with visible dye along the fissures under magnification.
Coating Treatment Change in color or luster Inconsistent surface and internal colors, with scratches and wear
Jewelry and gemstone names Optimization treatment methods Categories Processing effect Typical identification characteristics
Fluorite Heat treatment Optimization Improve or Change Color Color Stability, Cannot Be Identified by Conventional Instruments
Filling (colorless oil or wax) Optimization Improve durability Internal flash effect, lower transparency at fissures
Filling (colored oil or wax) Treatment Improve gemstone color and durability There are flash effects inside, magnifying the color distribution along the fissures.
Coating Treatment Change in color or luster Inconsistency between surface and internal colors, with scratches and wear
Irradiation Treatment Change color Color is stable, cannot be identified by conventional instruments
Natural Pearls Bleaching Optimization Improve color and other appearances Color is stable, no identification needed
Dyeing Treatment Change color Color is vivid, gloss is weak, surface color is deep at the pearl hole, internal color is light
Cultured pearls (pearls) Bleaching Optimization Improving color and appearance Color stability, no need for identification
Dyeing Treatment Change color Vivid color, weak gloss, surface color deep at the bead holes, internal color light
Irradiation Treatment Changing color The color can penetrate deeply, with a uniform surface color and a strong metallic luster.
Coral Bleaching Optimization Improve color and other appearances. Color is stable, no need for identification.
Filling (colorless oil or wax) Optimization Improve durability There is a sparkling effect inside, with lower transparency at the fissures
Filling (colored oil or wax) Treatment Improving gemstone color and durability There is a flash effect inside, magnifying the inspection of color distribution along the fissures.
Coating Treatment Improve or change color and luster. The surface and internal colors are inconsistent, with scratches and wear, and the surface luster is strong.
Dyeing Treatment Changing color The color is vivid, with the dye distributed along the fissures
Amber Pressure clearing Optimization Improve transparency Internally clean, can be sold as a natural product
Roasting color Optimization Change or improve color Often has a localized fired color, stable in florescence
Heat treatment Optimization Improve transparency Common internal lily-shaped inclusions
Recreate Treatment Compressing the powdered debris into large particle Granular structure, with visible "blood streaks" inside, and a strong luster.
Dyeing Treatment Changing color Vivid color, uneven distribution, with color concentrated in fissures or pits.
Coating Treatment Change in color, luster, and other appearances. The membrane layer is relatively thin, with parts often peeling off the surface, and bubbles may sometimes be seen at the junction between the membrane and the amber surface

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Section II Identification Characteristics of Common Natural Gemstones

Gemstone Name Color Chemical composition Refractive index Relative density Hardness Dispersion value UV fluorescence characterization (LW, SW) Magnified inspection and other features
Diamond None - light yellow, blue, green, red, black, etc. C, with small amounts of N, B, H 2.417 3.52 10 0.044 LW: None - strong blue, yellow fluorescence; SW: None - medium blue, yellow Light-dark crystalline inclusion, plumes, clouds, triangular thin-sectioned bi-crystals, growth lines, primitive crystal faces, etc. Thermally conductive, with 415nm, 453nm, and 478nm absorption lines, Type II b blue diamonds are electrically conductive.
Zircon Low type Medium type High type Colorless and blue, yellow, green, brown, purple, black, etc. ZrSiO4 1.810~1.984 3.90 ~4.80 6~7.5 0.038 LW: No-medium blue, green, green-yellow and orange fluorescence； SW: Weak fluorescence Mineral inclusions and healed fissures, surface scratches, and abrasions are common, and the rear faceted prisms are obvious, with more than 2~40 absorption lines visible, with 653.5nm characteristic absorption lines.
Ruby Medium-Deep Red Al2O3 1.762 -1.770 4.00 9 0.018 Weak-strong red fluorescence; the higher the chromium content, the stronger the fluorescence, the higher the Fe content, the weaker the fluorescence. Crystalline inclusions, gas-liquid two-phase inclusions, fingerprint inclusions, etc., flat growth texture and color band, typical chromium absorption spectra: 694nm, 692nm, 668nm, 659nm absorption lines, 620-540nm absorption band, 476nm, 475nm strong absorption lines, 468nm weak absorption lines, violet region of the whole absorption.
Sapphire Colorless and Blue, Pink, Yellow, Black, Green and gray, etc. Al2O3 No - weak LW: Weak - strong Red fluorescence; SW: Weak-medium red fluorescence, strong fluorescence in chromium-ionized stones Crystalline inclusions, gas-liquid inclusions, and fingerprint inclusions with flat, angular growth textures and color bands, some of which have starburst and color change effects. Strong iridescent, blue, green, and yellow sapphires have characteristic absorption spectra: 450nm absorption band or 450nm, 460nm, and 470nm absorption lines.
Garnet Aluminum Series Pyrope Orange, Red Mg2Al2(SiO4)3 1.714- 1.742 3.78 7~8 Demantoid (0.057)Other varieties are lower(0.022- 2.027) None; some colorless, light yellow, and light green grossular show weak orange-yellow fluorescence Needle-like inclusion, irregular rounded crystalline inclusion, 564nm broad absorption band
Almandine Deep Red, Purple Fe2Al2(SiO4)3 1.76-1.82 4.05 Needle-like inclusion, crystalline inclusion, etc., 504nm, 520nm, 573nm strong absorption bands
Spessartine Orange-orange-red Mn2Al2(SiO4)3 1.81 4.15 Irregular rounded crystalline inclusion, 410nm, 420nm, 430nm absorption lines
Calcium series Grossular Green, yellow, orange-red Ca2Al2(SiO4)3 1.740 3.61 Short columns or rounded crystalline envelopes, heat wave effec
Andradite Yellow, green, brown Ca2Fe2(SiO4)3 1.888 3.84 Characteristic “ponytail” envelope, 440 nm absorption band
Uvarovite Green Ca2Cr2(SiO4)3 1.850 3.75 Smaller particles that turn red in the Charles filter
Gemstone Name Color Chemical composition Refractive index Relative density Hardness Dispersion value UV fluorescence characterization (LW, SW) Magnified inspection and other features
Chrysoberyl Light yellow, yellow, green and tawny BeAl2O4 1.746 - 1.755 3.73 8-8.5 0.015 None; some yellow and yellow-green chrysoberyl’s are weakly fluorescent Fingerprints, fenestrations, filamentous inclusions, flat bands, bicrystalline, and stepped growth surfaces. Tricolor weakly-medium: yellow/green/brown, with a strong absorption band at 445nm.
Cat's eye Yellow, yellow-green, gray-green, maroon Weak to medium purplish red fluorescence Many parallel-arranged filamentous inclusions, fingerprint inclusions, and negative crystals exist. Cat's eye effect, weak trichromatic, with a strong absorption band at 445nm.
Alexandrite Daylight: green, yellow-green; Under incandescent light: orange-red, maroon Weak-medium purplish-red fluorescence, orange fluorescence under cathode rays Fingerprint inclusions, filamentous inclusions, color change effect, cat's eye effect. Strong trichromatic: green/orange-yellow/purple-red; red zone 680nm, 678nm strong absorption line, 665nm, 655nm, 645nm weak absorption line, yellow-green zone 580~630nm bah-hopping absorption band, blue zone 476nm, 476nm, 468nm weak absorption line, violet zone full absorption.
Hydrogrossular Green, yellow, red Ca3Al2(SiO4)3-x (OH)4x 1.72 3.47 7 - None Fine-grained cryptocrystalline structure, black punctate inclusions, reddish color in Charles filter, dark green with full absorption below 460nm.
Spinel Colorless, red, blue, yellow, purple, etc. MgAl2O4 1.718 3.60 8 0.020 Light red, red spinel: weak-moderate red fluorescence; green: no-moderate orange fluorescence Octahedral negative crystal envelope, red with 685nm. 684nm bow though absorption lines, 656nm weak absorption band, 595-490nm strong absorption band, blue, purple with 460nm strong absorption band.
Malachite Blue-green, green Cu2CO3(OH)2 1.655- 1.909 3.54-4.1 3.5-4 - None Striated, concentric ring structure, blistering in hydrochloric acid.
Olivine Yellowish green, green (Mg,Fe)SiO4 1.654- 1.690 3.34 6.5-7 0.020 None Disk-shaped gas-liquid two-phase inclusion, dark mineral inclusion, negative crystal, with 453nm, 477nm, and 497nm strong absorption.
Jadeite White, green, red, purple, gray, black, etc NaAlSi2O6 1.66 3.34 6.5-7 - None Dot and flake flashes (emerald), interwoven fiber structure with 437nm absorption lines, chromogenic with 630nm, 660nm, 690nm absorption lines.
Tourmaline Variety of colors, can be two-color or multi-color AB3C6(BO3)3 Si6O18(OH, F)4 1.624- 1.644 3.06 7~8 0.017 Generally absent, pink, red Chromium-containing: weakly red to purple Gas-liquid, tubular, and linear inclusion with longitudinal lines on the crystal column surface. Pink, red, green zone broad absorption band, sometimes visible 525nm narrow band, 451nm, 458nm absorption line; blue-green, red zone absorption, 498nm strong absorption band.
Gemstone Name Color Chemical composition Refractive index Relative density Hardness Dispersion value UV fluorescence characterization (LW, SW) Magnified inspection and other features
Topaz White, yellow, blue, green, etc. Al2SiO4(F,OH)2 1.619- 1.627 3.53 8 0.014 None - weak orange-yellow, yellow-green, with chromium: orange fluorescence Two or three-phase inclusions, inclusions of two or more immiscible liquids, mineral inclusions, negative crystals, etc. Longitudinal lines on the surface of the raw stone
Apatite Colorless, yellow, green, purple, and blue, etc. Ca5(PO4)3 (F, OH, Cl) 1.634- 1.638 3.18 5-5.5 - None, often produces phosphorescence when heated Gas-liquid inclusions, mineral inclusions, etc., yellow, colorless, and cat's-eye effect gemstones with 580nm absorption bilinear, blue with strong polychromatic
Andalusite Yellowish green, yellowish brown, green, pink AI2SiO5 1.634- 1.643 3.17 7-7.5 - None Needle-like inclusions, vacuolate variant with black carbon inclusions in cross-distribution, strong trichromatic: brown-yellow-green/brown-orange/maroon red
Euclase Colorless, light green, light blue BeAISiO4(OH) 1.652- 1.671 3.08 7~8 0.016 None Red and blue plate-like inclusions and ring bands, strong polychromatic, with 468nm and 455nm absorption bands, absorption in the green and red areas
Prehnite Colorless, light yellow, light green Ca2AI(AISi3O10) (OH)2 1.63 2.8-2.95 6-6.5 - None The fibrous structure is arranged in a radial pattern, with a weak absorption band at 438 nm, red under the Charles filter.
Turquoise Sky blue, blue, green. CUAI6(PO4)4 (OH)8•5H2O 1.61 2.76 5~6 - LW：None - weak yellowish green, blue； SW：None Often speckled structure, reticulated brown matrix
Nephrite Colorless, green, yellow, gray, black, etc. Ca2(Mg, Fe)5 Si8O22(OH)2 1.62 2.95 6-6.5 - None Fibrous interwoven structure, black envelope, and high-quality green can be seen in the red region fuzzy absorption lines
Rhodochrosite Pink, often with white, gray, and brown stripes MnCO3 1.597- 1.817 3.60 3~5 - None Striated and layered texture, blistering in hydrochloric acid, transparent stone with medium to strong polychromic: orange/red.
Emerald Green, blue-green, yellow-green Be3Al2(Si6O18) 1.577 〜 1.583 2.72 7.5-8 0.014 None - weak: dark red, weak red fluorescence under X-rays Fissure development, gas-liquid two-phase inclusions, three-phase inclusions, mineral inclusions, etc., medium-strong polychromic. 683nm, 680nm strong absorption lines, 662nm, 646nm weak absorption lines, 630~580nm partially absorbing bands, violet zone fully absorbing
Aquamarine Light green, blue-green, green-blue, light color. None, non-luminous under X-ray irradiation Gas-liquid two-phase inclusions, three-phase inclusions, mineral inclusions, parallel tubular inclusions, weakly to moderately polychromatic, with 537nm, 456nm weak absorption lines, 427nm strong absorption lines, the darker the color of the stone, the stronger the absorption line
Beryl Colorless, yellow, pink, red, blue, and black, etc. None Gas-liquid two-phase inclusions, various mineral inclusions, parallel tubular inclusions, etc. Polychromatic varies with the color of the gemstone; generally, the deeper the color, the stronger the polychromatic, with no weak iron absorption lines.
Gemstone Name Color Chemical composition Refractive index Relative density Hardness Dispersion value UV fluorescence characterization (LW, SW) Magnified inspection and other features
Dushan Jade White, green, blue, purple, yellow, black. Plagioclase Anorthite）, Zoisite 1.56, 1.70 2.90 6~7 - None Fibrous fine-grained structure, blue, blue-green spots, green part of the red color under the Charles filter
Serpentine jade Green, yellowish green, white, black, etc. Mg6(Si4O10) (OH)8 1.560- 1.570 2.57 2.5-6 - None, occasional weak green fluorescence Internal black mineral inclusion, white interwoven structure of strips, flakes, fibers
Labradorite Orange, yellow, gray, brownish red NaCaAlSi3O8 1.559- 1.568 2.70 6-6.5 - None Air-liquid inclusion, dark needle-like or plate-like mineral inclusion, halo effect, solubility development
Scapolite Colorless, Blue, Gray, Yellow, Maroon Na4(AlSi3O8)3 (Cl, OH) 1.550- 1.564 2.6-2.74 6 ~ 6.5 - None - strong: pink, orange, yellow Needle, parallel tubular inclusion, solid inclusion, negative crystal, etc. A pink gemstone with 663nm and 652nm absorption lines.
Quartz Colorless, purple, yellow, green, pink. SiO2 1.544- 1.553 2.66 7 - None Ribbons, gas-liquid inclusions, solid inclusions, negative crystals, etc., "bull's-eye" interferogram under orthogonal polarizing microscope.
Petrified wood Light yellow, maroon, brownish red, black, etc. SiO2•nH2O and C, H compound 1.54 2.5-2.91 7 - None Woody fiber-like structure, with wood grain
Quartzite (Aventurine) Green, gray, yellow, brown, orange, blue SiO2 1.54 2.64-2.71 7 - None, chromium-bearing quartzite: none-weak, grayish green or reddish Granular structure, often containing fuchsite, with 682nm, 649nm absorption band, with alluvial effect
Silicified asbestos Brownish red, brownish yellow, grayish blue, blue None Fibrous structure, with cat's eye effect, brownish yellow, brown-red called tiger's eye stone, gray-blue, blue called eagle's eye stone
Chalcedony (Agate) Various colors SiO2 1.54 2.60 6.5-7 - None, dyed chalcedony (agate) fluoresces strongly Cryptocrystalline structures, agate with banded and layered structures, can have a halo effect and cat's eye effect.
Lolite Blue-purple, colorless, off-white, etc. Mg2Al4Si5O18 1.542- 1.551 2.61 7-7.5 - None Color bands, gas-liquid inclusions, hematite flake inclusions, starburst effect, cat's eye effect, etc. Strong trichromaticity, weak absorption bands at 426nm and 645nm.
Amber Light yellow, yellow, fawn, red, green C10H16O, can contains H2S 1.537- 1.547 1.08 2-2.5 - LW: weak-strong blue, light yellow, light green; SW: none Bubbles, flow-like structures, animal and plant inclusions, hot needle melting and aromatic odor, electrically charged by friction, common anomalous matting
Sunstone Yellow, orange, brown, red XAlSi3O8, X are Na and Ca 1.537- 1.547 2.65 6 〜6.5 - None Common red or gold-colored plate-like hematite inclusions with alluvial gold effect
Ivory White, yellowish, light yellow, brown Protein, collagen, elastin 1.54 1.7-2.00 2~3 - LW: none; SW: weak-medium blue fluorescence Leuze grain, wave-like structure texture, softened by nitric acid, phosphoric acid, mammoth ivory partially petrified, mainly composed of SiO2
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Gemstone Name Color Chemical composition Refractive index Relative density Hardness Dispersion value UV fluorescence characterization (LW, SW) Magnified inspection and other features
Shell White, gray, yellow, etc. CaCO3 organic matter 1.530 〜 1.685 2.86 3~4 - None, stained shells fluoresce strongly Laminar structure, surface stromatolites, blistering in hydrochloric acid
Amazonite Green, Blue, Light Blue XAlSi3O8 X are Na and K 1.522- 1.530 2.56 6-6.5 - None Common green and white lattice-like coloration, solifluction development
Moonstone Colorless, Blue, Yellow 1.518- 1.526 2.58 None "Centipede-like" inclusion, needle-like, fingerprint-like inclusion, with halo colors
Natural pearl Colorless, Light Yellow, Light Blue, Pink, etc. CaCO3 and C, H chemical compound 1.530- 1.685 2.61-2.85 2.5 〜4.5 - Fluorescence varies from color to color, dyed pearls fluoresce more strongly Concentric radial lamellar structure, surface growth texture, pearly luster, blistering in hydrochloric acid, pearly luster
Cultured pearl Colorless, Light Yellow, Gold, Black, etc. 2.66 ~ 2.78 2.5~4 Nucleated cultured: thin pearl layer, concentric radial structure, surface texture; non-nucleated cultured: hollow in the center, pearl luster
Lazurite Blue, purple-blue (Na,Ca)8(AlSiO4)6 1.50 2.25 5~6 - LW: calcite-containing fraction fluoresces pink; SW: none Granular structure, often containing calcite, pyrite, etc., Charles color filter was Chu red, calcite content increases refractive index becomes larger
Natural glass Yellow, Green, Black, Orange, Red SiO2, can contain many impurities 1.49 2.36-2.40 5~6 - None Round or elongated bubbles, acicular crystalline inclusion, common anomalous extinction, and fracture surface can be seen as shell-like fracture
Marble Various colors CaCO3 1.486 〜 1.658 1.35, 2.65 3~4 - None, stained marble has weak to moderate fluorescence Granular structure, laminated or striated structure, blistering in hydrochloric acid
Coral Light to dark red, orange, white, black, etc. CaCO3 1.486- 1.658 1.35, 2.65 3~4 - None, Gelatinized stones have strong fluorescence Concentric rings in cross-section, parallel corrugated texture in longitudinal section, blistering in hydrochloric acid
Sodalite Dark blue, violet blue Na8Al6Si6O24Cl2 1.483 2.25 5~6 - Weak-medium: orange or orange-red Granular structure, white veins, flash on the disintegrated surface, reddening under the filter lens
Opal White, orange-red, blue, green, black, etc. SiO2 • nH2O 1.450, can be as low as 1.37 2.15 5~6 - Black or white: none-medium; white, light blue, green or yellow; fire opal: none-medium; greenish brown: phosphorescent The color spot is an irregular sheet; the color spot boundary is not obvious; the surface is silky luster and the color change effect
Fluorite Colorless, Green, Blue, Yellow, Pink, Purple CaF2 1.434 3.18 4 - Medium-strong fluorescence, varied colors, strong phosphorescence Two-phase or three-phase inclusion, obvious color band, the development of the decohesion is triangular, part of the color change effect

Section III Identification Characteristics of Common Synthetic Gemstones

Gemstone Name Color Synthesis method Chemical composition Refractive index Relative density Hardness Dispersion value UV fluorescence characterization (LW, SW) Magnified inspection and other features
Synthetic Moissanite Colorless - light yellow, light blue, light green, etc. Chemical Vapor Phase Precipitation SiC 2.648 ~ 2.691 3.22 9.25 0.104 None - weak orange fluorescence Punctate, filamentous inclusion with significant ghosting
Synthetic rutile Colorless, light yellow, light blue, green, etc. Flame melting method TiO2 2.616 〜 2.691 4.26 6~7 0.330 None Re-imaging is obvious, clean inside, occasional bubbles, yellow and blue color
Synthetic diamond Colorless, yellow, green, blue, brown, etc. High Temperature High Pressure C 2.417 3.52 10 0.044 LW: none; SW: weak-strong, stronger yellow and yellow-green phosphorescence Metal inclusions such as iron and nickel, black graphite inclusions, magnetism
Colorless, Tawny, Blue, etc. Chemical Vapor Phase Precipitation LW: none; SW: none - medium, orange fluorescence Dotted inclusions, laminated flat growth texture
Strontium titanate Colorless, Green Flame melting SrTiO3 2.409 5.13 5〜6 0.190 None Internally clean, surface scratches
Synthetic Cubic Zirconia Colorless, pink, red, blue, green, purple, black, etc. Cold Crucible Shell Fusion ZrO2 2.15 5.80- 6.00 8.5 0.060 LW: none - medium orange; SW: none - medium yellow, yellow-green Internally Clean, Occasional Bubbles
Gadolinium gallium garnet Colorless, Light Yellow, etc. Flame melting method Cd5Ga5O12 1.970 7.05 6~7 0.045 None - weak: orange fluorescence Internal bubbles, metal inclusions, powdered raw material inclusions, adamantine luster
Yttrium aluminum Colorless, Green, Blue, etc. Crystal lifting method Y3AI5O12 1.833 4.50- 4.60 8 0.028 None - weak: orange fluorescence, yellow with strong yellow fluorescence Internally Clean, Occasional Elongated Bubbles Visible
Synthetic ruby Medium-Dark Red Flame melting Al2O3 1.762 〜 1.770 4.0 9 0.018 Medium-strong: red fluorescence Curved Growth Patterns, White Powdered Inclusion
Hydrothermal method Medium-strong: red fluorescence Fingerprint Inclusion, Flat Growth Texture
Flux method Medium-strong: red fluorescence Flux Residue, Metal Clad
Crystal lifting None - Medium: red fluorescence Internally Clean, Occasional Elongated Bubbles
Synthetic Sapphire Colorless, Blue, Yellow, Green, Pink, etc. Flame-melting Al2O3 1.762- 1.770 4.0 9 0.018 Fluorescence characteristics change with different colors Curved Growth Texture, White Powdered Clad Body
Hydrothermal Fingerprint Inclusion, Flat Growth Texture
Flux method Flux Residue, Metal Clad
Crystal lifting Internally Clean, Occasional Elongated Bubbles
Gemstone Name Color Synthesis method Chemical composition Refractive index Relative density Hardness Dispersion value UV fluorescence characterization (LW, SW) Magnified inspection and other features
Synthesized Starlight Red and Sapphire Red, light yellow, light blue, green, etc. Flame melting AI2O3•TiO2 1.762- 1.770 4.0 9 0.018 Synthetic Star Ruby: medium-strong red; Synthetic Star Sapphire: LW, none; SW, weak blue-white Uniform thickness of star lines, clear intersections of star lines, starlight floating on the surface, curved growth lines visible inside, white powdery inclusions
Synthetic Emeralds Green color Hydrothermal method BeAlSi2O6 1.560- 1.578 2.65 ~ 2.73 7.5 0.014 Medium-strong: red Seed crystals, water ripple texture, nail-like inclusions; only type I water in the structure tested by infrared spectroscopy
Flux method Medium-strong: red Flux Residue, Metal Clad
Synthetic Alexandrite Daylight: green; incandescent: red Crystal lifting BeAl2O4 1.740 〜 1.749 3.73 8.5 0.018 Medium-strong: red Internally clean, occasional elongated bubbles visible, curved growth lines
Synthetic Spinel Blue, red, purple, pink, colorless, etc. Flame melting MgAl2O4 1.728 3.64 8 0.020 Chromium-bearing: none - medium red fluorescent Cobalt: LW red, SW blue-white Internally clean, occasional bubbles visible, reddening under Charles filter, unusual matting
Synthetic Turquoise Green, blue, etc. Chemical precipitation CUAl6(PO4)4 (OH)8•5H2O 1.60- 1.65 2.6 ~ 2.9 5~6 - None Fine-grained structure, black to dark brown reticulated iron lines
Synthetic Aquamarine Light blue, blue, etc. Hydrothermal BeAlSi2O6 1.575- 1.583 3.64 7.5 0.014 None Clear boundaries around seed crystals, crystalline inclusion, only type I water in infrared spectroscopic tests
Synthetic Lapis Lazuli Blue, indigo Chemical precipitation Differences in composition from natural lapis lazuli 1.55 2.33- 2.53 4.5 - None Uniform distribution of pyrite, flat corners, uniform size
Synthetic Crystal Colorless, purple, green, blue, yellow, etc. Hydrothermal SiO2 1.544- 1.553 2.65 7 0.012 None Seed crystals, “table dust” inclusion, flat color bands, warm to touch
Synthetic Opal White, black, blue, etc. Chemical precipitation SiO2•nH2O 1.42-1.46 1.97- 2.20 5.5~ 6.5 - None Clearly delineated color spots, mosaic structure, columnar color spots, lizard skin-like structure
Plastic Various colors Others Variable composition 1.46-1.47 1.05- 1.55 1.5-3 - Variable, often chalky Internal flow patterns, bubbles, mold features, often with scratches and pits on the surface
Glass Various colors Others SiO2 1.48-1.70 2.30 〜 4.50 5〜6 - Variable, often chalky Internal flow pattern, air bubbles, shell-like structure on the fracture surface, with mold features.
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Heman

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Hi Dear,

I am Heman, dad and hero to two awesome kids. I am glad to share my jewelry experiences as an expert in jewelry products. Since 2010, I have served 29 clients from all over the world, such as Hiphopbling and Silverplanet, assisting and supporting them in creative jewelry design, jewelry product development and manufacturing.

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Heman

Jewelry Products Expert

Hi Dear,

I am Heman, dad and hero to two awesome kids. I am glad to share my jewelry experiences as an expert in jewelry products. Since 2010, I have served 29 clients from all over the world, such as Hiphopbling and Silverplanet, assisting and supporting them in creative jewelry design, jewelry product development and manufacturing.

If you have any questions about jewelry product, feel free to call or email me and let’s discuss a appropriate solution for you, and you will get free jewelry samples to check the craftsmanship and jewelry quality details.

Let’s grow together!

CONTACT ME

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