Gems Testing Machine: Composition, Specifications, and How It Supports Industry Projects

Types of Gem Testing Machines

Gem testing machines are essential tools in gemology, used to authenticate, identify, and evaluate gemstones. Each type operates on distinct scientific principles and offers unique advantages depending on the testing needs. From basic hardness assessments to advanced spectroscopic analysis, these instruments ensure accuracy, reliability, and non-destructive evaluation of precious and semi-precious stones.

Refractive Index Measurement

Determines how light bends as it passes through a gemstone, providing a key identifier based on the material’s optical density.

Advantages

• Non-destructive and chemical-free testing
• Quick and repeatable results
• Highly effective for distinguishing between natural and synthetic stones
• Portable models available for field use

Limitations

• Requires skilled interpretation of readings
• Less effective on cut stones with small facets
• Limited accuracy with doubly refractive or heavily included stones

Best for: Gemologists, jewelers, and laboratories requiring fast optical identification

Specific Gravity (S.G.) Tester

Measures the density of a gemstone by comparing its weight in air versus in water, helping to identify the stone based on known specific gravity values.

Advantages

• Highly accurate for identification
• Effective for differentiating look-alike stones (e.g., sapphire vs. synthetic spinel)
• Inexpensive and reliable method when done correctly
• Works well with rough and polished stones

Limitations

• Requires precise weighing equipment
• Time-consuming for large batches
• Sensitive to air bubbles and surface tension

Best for: Gem collectors, dealers, and labs handling bulk identification

Gemstone Hardness Tester

Assesses scratch resistance using the Mohs scale (1–10), helping determine whether a stone is suitable for jewelry or has been misidentified.

Advantages

• Simple, portable, and easy to use
• Immediate results for preliminary screening
• Useful for educational demonstrations
• Helps prevent damage during setting or wear

Limitations

• Potentially damaging to the stone (micro-scratches)
• Not suitable for finished or valuable gems
• Less precise than other methods

Best for: Jewelry workshops, gem education, and initial stone screening

Spectroscope

Analyzes the absorption spectrum of light passing through a gemstone, revealing characteristic spectral lines unique to certain elements and gem types.

Advantages

• Non-invasive and highly informative
• Can identify trace elements (e.g., chromium in emeralds)
• Helps distinguish natural from synthetic stones
• Provides insight into origin and treatment history

Limitations

• Requires strong light source and steady hand
• Interpretation demands expertise
• Less effective on colorless or weakly colored stones

Best for: Advanced gemologists, research labs, and provenance verification

Gem Analyzer (Advanced Multi-Technique Devices)

Utilizes technologies like Raman spectroscopy and UV-Vis absorption to analyze chemical composition, crystal structure, and optical properties without damaging the sample.

Advantages

• Highly accurate and comprehensive analysis
• Non-destructive and automated reporting
• Identifies treatments, synthetics, and simulants
• Fast processing of multiple stones with database matching

Limitations

• High initial cost and maintenance
• Requires technical training and controlled environment
• Larger footprint; not portable

Best for: Wholesale gem dealers, certification labs, and academic research

Machine Type	Accuracy	Destructive?	Speed	Best Use Case
Refractive Index Measurement	High	No	Fast	Optical identification, gem sorting
Specific Gravity Tester	Very High	No	Moderate	Precise density-based identification
Gemstone Hardness Tester	Moderate	Yes (minor)	Fast	Field testing, education
Spectroscope	High	No	Moderate	Origin and treatment analysis
Gem Analyzer (Raman/UV-Vis)	Exceptional	No	Very Fast	Lab certification, wholesale verification

Expert Tip: For the most reliable gem identification, combine multiple testing methods. For example, use refractive index and specific gravity together to narrow down possibilities, then confirm with a spectroscope or gem analyzer for definitive results.

Design and Functionality of Gemstone Testing Machines

Modern gem testing machines integrate advanced technologies and precision engineering to perform multiple diagnostic tests efficiently and accurately. These tools are essential in gemology, jewelry appraisal, and quality control, enabling professionals to authenticate, classify, and evaluate gemstones without causing damage. From traditional optical instruments to digital analyzers, each device serves a unique purpose in the comprehensive assessment of gem properties.

Core Technologies in Gem Testing Equipment

Refractive Index Measurement

The refractometer is a cornerstone tool in gem identification, designed to measure how light bends as it passes through a gemstone—a property known as refractive index (RI). The device features a high-density glass hemisphere (often made of lead glass or flint glass) that acts as a prism. A small drop of contact liquid ensures optimal optical coupling between the gem and the glass surface.

The gem is placed on the "spot" (measurement area), and a controlled light source illuminates the interface. A skilled gemologist peers through an eyepiece to observe the shadow boundary on a calibrated scale, which corresponds to the RI value. Because it operates on optical principles alone, the refractometer requires no electrical power, making it highly reliable in fieldwork or remote settings.

This simplicity, durability, and accuracy make it a favorite among jewelers and gemologists for rapid, non-destructive testing of transparent and translucent stones.

Specific Gravity (S.G.) Tester

The specific gravity tester determines a gemstone’s density by measuring its weight in air versus its weight in water—a principle based on Archimedes’ law. Constructed with a high-quality metal frame for stability, the device includes a precision balance and a submerged water tank with a fine mesh basket or suspension wire.

Some advanced models incorporate a buoyant float to assist in lifting denser stones, improving measurement accuracy. By calculating the ratio of the stone’s weight in air to the loss of weight in water, the S.G. value is derived. This method is particularly effective in distinguishing natural gemstones from synthetic or imitation materials, which often have different density profiles.

As a chemical-free, non-destructive technique, the S.G. test is ideal for high-volume environments such as wholesale gem markets, jewelry stores, and appraisal labs where fast, reliable identification is crucial.

Gem Hardness Tester

Hardness is a key diagnostic property in gemology, typically assessed using the Mohs scale (1–10). The gem hardness tester features a robust metal body housing a precisely mounted diamond tip—rated at 10 on the Mohs scale—capable of scratching softer minerals.

The device allows controlled application of pressure to the gem’s surface, enabling professionals to determine whether a scratch occurs without damaging harder stones. Some models include a built-in Mohs scale reference guide for immediate comparison and classification.

While this test is semi-destructive (microscopic scratching may occur), it is invaluable in field identification, especially when differentiating between look-alike materials. It's widely used in gem labs, mining operations, and retail settings where quick verification of material authenticity is required.

Gemstone Spectroscope

The spectroscope is a powerful analytical tool that reveals the absorption spectrum of a gemstone—its unique "fingerprint" of light absorption at specific wavelengths. It consists of a metal-bodied tube with a narrow entrance slit, a collimating lens, and a diffraction grating or prism that disperses light into its spectral components.

When a beam of light passes through the gem and into the spectroscope, the resulting spectrum displays dark lines or bands where the stone absorbs certain wavelengths. These patterns help identify the presence of specific elements (e.g., chromium in rubies, iron in peridot) and distinguish natural stones from synthetics or imitations.

Adjustable prism angles and precision slits ensure optimal light alignment, minimizing artifacts and enhancing clarity. Due to its ability to provide rapid, non-invasive chemical insights, the spectroscope is indispensable for gemologists, auction houses, and dealers handling high-value or rare specimens.

Gem Analyzer (Advanced Multi-Function Device)

Modern gem analyzers represent the pinnacle of gem testing technology, combining multiple scientific methods—such as Raman spectroscopy, infrared absorption, and photoluminescence—into a single, user-friendly instrument. These devices analyze the gem’s chemical composition, crystal structure, and trace element content without any physical alteration.

Equipped with a high-resolution sensor and integrated database of thousands of gem types, the analyzer delivers instant results via a digital interface. It can differentiate between natural and lab-grown diamonds, detect heat treatment in sapphires, and identify composite stones or fillers.

Its non-destructive nature, speed, and accuracy make it ideal for gem dealers, auctioneers, and certification laboratories. By eliminating the need for sample extraction and enabling bulk evaluation, the gem analyzer significantly streamlines the valuation and authentication process in commercial and academic settings.

Comparison of Key Gem Testing Methods

Test Type	Principle	Best For	Destructive?
Refractive Index	Light bending in gem material	Identifying gem species	No
Specific Gravity	Density comparison (air vs. water)	Distinguishing naturals from fakes	No
Hardness Test	Scratch resistance (Mohs scale)	Field identification	Semi (micro-scratch)
Spectroscopy	Light absorption patterns	Elemental analysis	No
Gem Analyzer	Multimodal scientific analysis	Authentication & valuation	No

Key Benefits Across Gem Testing Technologies

Non-Destructive Analysis: Most modern gem testers preserve the integrity of valuable stones, ensuring they remain marketable after testing.

Rapid Results: From simple refractometers to digital analyzers, these tools deliver quick assessments crucial in fast-paced retail or auction environments.

High Accuracy: When used correctly, these instruments provide scientifically valid data that supports certification and insurance valuation.

Versatility: Many devices can test a wide range of gem types, from diamonds and sapphires to emeralds and synthetic materials.

Durability: Built with robust materials like metal housings and hardened glass, these tools withstand daily use in professional settings.

Important: While gem testing machines enhance accuracy, proper training and calibration are essential. Misinterpretation of results or improper use (e.g., excessive pressure in hardness tests) can lead to incorrect identification or damage. Always follow manufacturer guidelines and use certified reference materials when available. For legal or high-value assessments, combine instrumental analysis with expert visual examination.

Scenarios of Gem Testing Machines

Gem testing machines play a vital role across the jewelry and gemstone industry by accurately verifying authenticity, composition, and quality. These advanced tools combine optical, thermal, and electrical analysis to distinguish natural gems from synthetics or imitations. From retail stores to high-end laboratories, the use of gem testers ensures trust, precision, and efficiency in every transaction involving precious stones.

Jewelry Stores

In retail jewelry environments, gem testing machines are essential for maintaining product integrity and customer confidence. Staff use handheld testers to quickly verify the authenticity of diamonds and colored gemstones before setting them into rings, necklaces, or earrings.

• Ensures that all stones used in custom or pre-made jewelry are genuine
• Prevents costly mistakes from unknowingly using lab-grown or simulated stones
• Provides instant verification during buy-backs or trade-ins of customer jewelry
• Supports transparent sales conversations—customers feel assured knowing their purchase has been professionally tested

Key benefit: Real-time verification helps maintain brand reputation and reduces liability.

Gemstone Wholesalers

Wholesalers dealing with bulk quantities of rough or cut gemstones rely on testing equipment to streamline inventory management and ensure accurate grading. These machines help sort large batches efficiently, identifying natural vs. synthetic stones and detecting treatments like fracture filling or irradiation.

• Speeds up the evaluation process when receiving shipments from miners or cutters
• Reduces risk of overpaying for misrepresented or enhanced stones
• Facilitates accurate pricing based on verified gem type and quality
• Supports compliance with international trade standards and disclosure requirements

Pro tip: Use multi-functional testers capable of analyzing diamonds, moissanite, and common colored gems like sapphires and emeralds.

Gemological Laboratories

Professional gem labs utilize advanced testing machines—including spectrometers, refractometers, and photoluminescence analyzers—to produce detailed certification reports. These instruments go beyond basic identification, revealing growth origin (natural vs. lab-created), treatment history, and geographic sourcing clues.

• Enables issuance of authoritative grading reports for diamonds and colored stones
• Supports research and forensic analysis in cases of suspected fraud
• Automated data logging improves consistency and traceability
• High-throughput systems allow labs to process hundreds of stones daily without sacrificing accuracy

Technical insight: FTIR (Fourier Transform Infrared) spectroscopy is often used to detect polymer fillings in emeralds and other treated gems.

Auction Houses

Prestigious auction houses employ gem testing machines to authenticate high-value lots before public sale. Each stone is rigorously examined to confirm its identity, quality, and provenance—critical factors that influence bidding interest and final prices.

• Builds credibility with collectors and investors who demand verified pieces
• Identifies undisclosed enhancements that could affect value
• Allows curators to confidently present detailed descriptions in catalogs
• Protects the auction house from legal disputes over misrepresentation

Critical practice: Combine machine testing with expert gemologist review for the highest level of assurance.

Appraisal Services

Professional appraisers use gem testing machines to accurately assess the value of jewelry brought in by individuals for insurance, estate planning, or resale purposes. These tools provide objective data on stone identity, weight, clarity indicators, and potential treatments.

• Increases appraisal accuracy and defensibility in insurance claims
• Speeds up the evaluation process, allowing more clients to be served per day
• Helps identify overlooked valuable stones in inherited or vintage pieces
• Documents findings with digital integration for report generation

Best practice: Always disclose testing methods used in appraisal reports to enhance transparency.

Additional Applications

Beyond the core industries, gem testing technology supports various niche and emerging sectors:

• Custom Designers: Verify materials before crafting bespoke pieces
• Estate Buyers: Quickly assess mixed lots of jewelry for resale potential
• Insurance Adjusters: Confirm authenticity during claims processing
• Antique Dealers: Identify historical gem types and detect modern replacements
• E-commerce Platforms: Provide verification for online sellers to build buyer trust

Emerging trend: Portable, AI-enhanced testers are making professional-grade analysis accessible to smaller businesses.

Expert Recommendation: Whether you're running a small jewelry store or a large lab, invest in a reliable, multi-stone capable tester with regular calibration. Training staff in proper usage ensures consistent results and maximizes return on investment. Remember: a single misidentified stone can damage your reputation—accurate testing is not just a tool, it's a foundation of trust in the gem and jewelry trade.

Industry	Primary Use Case	Common Testing Methods	Frequency of Use
Jewelry Stores	Authenticity verification before sale or repair	Diamond testers, thermal probes, loupe + UV	Multiple times daily
Gemstone Wholesalers	Batch sorting and quality control	Spectroscopy, conductivity tests, magnification	Daily to weekly
Gem Labs	Certification and origin analysis	FTIR, Raman spectroscopy, refractometry	Continuous, high volume
Auction Houses	Pre-sale authentication and valuation support	Advanced imaging, fluorescence analysis, microscopy	Per auction cycle
Appraisal Services	Value assessment and documentation	Combination of handheld testers and visual inspection	Per client appointment

Key Features to Look for in Gem Testing Machines

• Multifunctionality: Ability to test diamonds, moissanite, cubic zirconia, and colored stones
• Portability: Compact, battery-operated models ideal for on-site evaluations
• Digital Display: Clear readouts with pass/fail indicators or numerical values
• Data Connectivity: USB or Bluetooth for report integration and record keeping
• Calibration Alerts: Reminders to maintain accuracy over time
• Durability: Rugged design suitable for frequent handling in busy environments

Specification & Maintenance of Gem Testing Machines

Proper understanding, adherence to technical specifications, and consistent maintenance of gem testing equipment are essential for ensuring accurate, reliable, and repeatable results. These instruments are critical tools in gemology, used by jewelers, appraisers, and laboratories to identify and authenticate precious and semi-precious stones. Maintaining optimal performance not only extends the lifespan of the equipment but also safeguards the integrity of gem analysis.

Safety & Accuracy Warning: Always handle gem testing instruments with care. Contamination, improper handling, or environmental interference can lead to inaccurate readings, misidentification, or permanent damage. Use appropriate protective gear when necessary and follow manufacturer guidelines for calibration and operation.

Detailed Overview of Key Gem Testing Instruments

• Gems Analyzer – Key Features, Care, and Precautions

  This advanced electronic analyzer utilizes spectral imaging, thermal conductivity, and optical sensors to rapidly identify gemstones without requiring destructive sampling. Its non-invasive technology allows for quick and safe testing of mounted or delicate stones, making it ideal for retail environments, laboratories, and appraisal centers.

  • Power Requirements: Operates on standard AC power (110–240V); ensure stable voltage supply to prevent internal circuit damage.
  • Data Management: Stores identification records and spectral data via integrated software; back up data regularly to prevent loss.
  • Environmental Sensitivity: Avoid use near strong electromagnetic fields (e.g., microwaves, motors), which can interfere with sensor accuracy.
  • Cleaning & Maintenance: Wipe exterior surfaces with a soft, dry microfiber cloth. Use manufacturer-approved cleaning solutions for the sensor window—never apply liquids directly.
  • Handling: Protect from impacts, drops, and liquid exposure. Always cover the sensor when not in use to prevent dust accumulation.
• Refractive Index (RI) Tester – Key Features, Care, and Precautions

  The refractometer measures how light bends as it passes through a gemstone, a fundamental property used to identify materials. This optical instrument is portable, requires no electricity, and delivers precise RI values critical for distinguishing between natural, synthetic, and imitation stones.

  • Lens Care: Keep the glass hemisphere and contact prism meticulously clean. Use lens paper and refractive index fluid (e.g., methylene iodide) sparingly and only as directed.
  • Fingerprint Prevention: Avoid touching the prism surface with bare fingers—oils can distort readings and degrade the coating over time.
  • Storage: Store in a padded, dry case with the protective cap on. High humidity or temperature fluctuations can damage internal optics.
  • Calibration: Regularly calibrate using a known standard (e.g., zircon or glass slide) to maintain measurement accuracy.
  • Usage Tip: Apply only a small drop of contact liquid; excess fluid can seep into the instrument and cause internal damage.
• Specific Gravity (S.G.) Tester – Key Features, Care, and Precautions

  This hydrostatic balance system determines a gem’s density by comparing its weight in air to its weight in water—a reliable method for identifying gem species, especially when combined with other tests. It is effective for both loose and mounted stones of various sizes.

  • Water Exposure: Prevent water from entering the electronic scale or mechanical components. Dry all parts thoroughly after each use.
  • Sample Preparation: Clean stones with mild soap and water before testing. Avoid chemical solvents that may leave residues affecting buoyancy.
  • Scale Protection: Never place heavy or sharp objects directly on the scale. Use the suspension basket or tray as designed.
  • Maintenance: Check for air bubbles during immersion—these can skew results. Regularly inspect the water reservoir for contamination.
  • Accuracy Tip: Use distilled water to prevent mineral buildup and ensure consistent readings.
• Gem Hardness Tester – Key Features, Care, and Precautions

  This mechanical device assesses a gem’s resistance to scratching using standardized hardness points (e.g., Mohs scale). It features durable metal construction and precision tips for controlled testing, primarily used in laboratory settings where non-destructive methods are insufficient.

  • Tip Maintenance: Clean testing points after each use with a soft brush. Replace worn or damaged tips immediately to avoid false readings.
  • Controlled Force: Apply consistent, light pressure—excessive force can damage both the stone and the instrument.
  • Handling: Avoid dropping or jarring the device. Internal mechanisms are sensitive and can become misaligned.
  • Use Caution: Only perform hardness tests on unmounted stones when identification is uncertain and damage is acceptable.
  • Safety Note: Always wear eye protection when conducting scratch tests to guard against stone fragments.
• Spectroscope – Key Features, Care, and Precautions

  A spectroscope disperses light reflected or transmitted through a gemstone into its component wavelengths, revealing absorption lines unique to specific elements. This non-destructive tool is invaluable for identifying colored stones, detecting treatments, and differentiating natural from synthetic gems.

  • Optical Integrity: Never touch internal diffraction grating or prism surfaces. Fingerprints or dust can obscure critical spectral lines.
  • Cleaning: Use compressed air or a soft brush to remove dust. Lens caps should be worn when not in use.
  • Handling: Protect from drops and shocks—internal alignment is precise and easily disrupted.
  • Light Source: Use a consistent, bright white light (e.g., daylight LED) for best results. Avoid fluorescent lighting, which can distort spectra.
  • Storage: Keep in a dry, temperature-stable environment to prevent condensation inside the tube.

Instrument	Primary Function	Maintenance Frequency	Critical Care Tips
Gems Analyzer	Rapid non-destructive identification via spectral analysis	After each use / Monthly calibration	Keep sensor clean; avoid electromagnetic interference
Refractive Index Tester	Measure light bending in gemstones	Before and after each use	Never touch prism; calibrate daily
Specific Gravity Tester	Determine density via hydrostatic weighing	After each use / Weekly inspection	Use distilled water; dry components thoroughly
Gem Hardness Tester	Assess scratch resistance (Mohs scale)	After each use / Tip inspection	Replace worn tips; use light pressure
Spectroscope	Analyze absorption spectra for identification	Before use / As needed	Protect optics; use proper lighting

Expert Tip: Establish a routine maintenance log for all gem testing instruments. Record calibration dates, cleaning schedules, and any anomalies observed during use. This practice enhances accountability, supports quality assurance, and helps detect early signs of wear or malfunction.

General Best Practices for Gem Testing Equipment

• Always consult the manufacturer’s manual for model-specific instructions and safety guidelines.
• Store all instruments in a clean, dry, temperature-controlled environment away from direct sunlight.
• Use only recommended cleaning agents and tools to avoid damaging sensitive components.
• Schedule professional servicing or calibration at least once per year, or more frequently with heavy use.
• Train all users on proper handling techniques to minimize human error and equipment damage.
• Label and organize accessories (e.g., fluid bottles, test tips, calibration stones) to prevent loss or contamination.

Maintaining gem testing machines is not just about preserving equipment—it's about ensuring scientific accuracy and professional credibility. Whether used in a high-volume jewelry store or a forensic gemology lab, these instruments demand respect, precision, and proactive care. By following the guidelines outlined above, users can achieve consistent, trustworthy results and extend the operational life of their valuable tools.

Frequently Asked Questions About Gem Testing Machines

Q1: What is a gem testing machine's primary purpose?

A1: The primary purpose of a gem testing machine is to accurately identify, verify authenticity, and assess the quality of gemstones. These devices are essential tools in jewelry appraisal, gemology, and retail settings, helping professionals and enthusiasts distinguish natural stones from synthetic or imitation materials. By analyzing physical and optical properties, gem testers ensure confidence in valuation, certification, and purchasing decisions.

Q2: Do gem testing machines damage the stone during analysis?

A2: No, the majority of modern gem testing machines are designed to be non-destructive and safe for use on delicate gemstones. They rely on advanced technologies such as spectroscopy, thermal conductivity measurement, and refractometry that do not require scratching, heating, or otherwise altering the stone. This makes them ideal for evaluating valuable or heirloom pieces where preservation is critical.

• Thermal Conductivity Testers: Commonly used to differentiate diamonds from simulants like cubic zirconia without contact damage.
• Refractometers: Use a small drop of contact liquid but leave no residue or surface marks.
• Spectrometers and UV-Vis Analyzers: Perform optical analysis without any physical interaction.

Always follow manufacturer guidelines to ensure safe handling and avoid accidental scratches from improper placement.

Q3: What types of tests can gem testing machines perform?

A3: Gem testing machines are capable of conducting a wide range of scientific evaluations to determine a gemstone’s characteristics and authenticity. Key tests include:

• Authenticity Verification: Distinguishes natural gems from lab-created or imitation stones (e.g., detecting moissanite vs. diamond).
• Refractive Index (RI) Measurement: Identifies gem type based on how light bends as it passes through the material.
• Specific Gravity (SG) Testing: Measures density relative to water, useful for identifying certain gem families.
• Hardness Assessment: Some advanced systems estimate hardness using controlled pressure methods (though traditional scratch testing is avoided).
• Color Analysis: Utilizes spectrophotometry to evaluate hue, tone, and saturation, important for grading colored stones.
• Fluorescence and UV Response: Detects reactions under ultraviolet light, which can help identify treatments or origins.

High-end models may integrate digital imaging, AI-assisted classification, and database matching for comprehensive gem identification.

Q4: Are gem testing machines suitable for beginners?

A4: Yes, many gem testing devices are beginner-friendly, especially compact digital testers designed for hobbyists, students, and small jewelers. Simple handheld models often feature LED indicators or smartphone connectivity with intuitive apps that guide users through the process with minimal training.

• Beginner-Friendly Tools: Include portable diamond testers, basic refractometers, and UV lamps with clear instructions.
• Learning Curve: Entry-level users may need practice interpreting results, particularly when dealing with treated or composite stones.
• Professional-Grade Equipment: More complex instruments like Fourier Transform Infrared (FTIR) spectrometers or automated grading systems require formal training and experience to operate effectively.

For those new to gemology, starting with a multi-function入门 tester and pairing it with educational resources can provide a solid foundation for accurate gem evaluation.

Q5: How often should a gem tester be calibrated?

A5: Regular calibration is crucial to maintain the accuracy and reliability of gem testing equipment. The frequency depends on usage intensity and environmental conditions:

• Light to Moderate Use: Calibrate every 6–12 months to ensure consistent performance.
• Heavy Daily Use (e.g., labs, retail stores): Recalibrate every 3–6 months or after detecting inconsistent readings.
• After Impact or Environmental Changes: If the device is dropped or exposed to extreme temperatures/humidity, immediate recalibration is recommended.

Many professional-grade testers come with built-in calibration modes and reference standards (like a calibration glass slide or thermal probe check). Always refer to the manufacturer’s manual for model-specific procedures and use certified calibration tools to maintain precision. Proper maintenance extends the lifespan of the device and ensures trustworthy results in gem identification.