Siziviki Diamond Tester Pen Pro
4.1Editor score
Detailed LED indicator system
Video guide for operation
Affordable price point
In this guide
Choosing the right Diamond Tester is essential for anyone who deals with gemstones regularly. Whether you are a jeweler, collector, or casual buyer, accuracy matters. A good tester distinguishes real diamonds from simulants like cubic zirconia and glass using thermal conductivity or UV fluorescence.
We have compared ten highly rated Diamond Tester units based on their features, accuracy, ease of use, and user feedback. This list includes portable pens, professional handheld devices, and multi-function testers suitable for different needs and budgets.
Each pick highlights specific strengths and potential limitations to help you make an informed decision. Note that availability and pricing may change over time, so always verify current details before purchasing your chosen model.
Top 3 Picks for Best Diamond Tester
Valkynos Professional Diamond Tester Pen
4.3Editor score
365nm UV light for fluorescence
Fast 0.5s detection time
Includes protective case and pouch
Presidium Instruments Gem Tester II
4.2Editor score
Assisted thermal calibration included
Thinnest retractable probe tip
Differentiates 16 gemstone types
Top 10 Best Diamond Tester in 2026 Compared
The following comparison table presents key specifications for each Diamond Tester model to help you quickly identify the features that matter most for your testing needs.
ProductsSpecificationsEditor scorePrice
Editor's Choice
Valkynos Professional
Thermal conductivity sensor
365nm UV light
0.5s response time
9V battery powered
4.3Editor score
Editor's Choice
Siziviki Pro
Multi-level LED indicator
Requires 30s preheat
9V battery included
Video guide provided
4.1Editor score
Best Premium
Diamond Selector II
LCD display and LEDs
Audible sound alerts
Bare hands required
Leather pouch case
4.0Editor score
Presidium Gem Tester II
Analog dial display
Self calibration feature
16 gemstone types
Retractable probe tip
4.2Editor score
Professional Tester Pen UV
UV fluorescence detection
0.5s instant response
Includes tweezers
9V battery included
4.3Editor score
HMKIS Diamond Tester
Type-C power option
Includes 60X loupe
LCD display unit
Non-rechargeable design
4.0Editor score
GemOro UltraTester 3+
4-way color testing
UV moissanite tech
Rechargeable batteries
Includes carrying case
3.8Editor score
Purity Testing Kit
Gold silver platinum kit
Diamond tester included
Touchstone for testing
Acid neutralizer bonus
4.3Editor score
Presidium Diamond Mate C
Rechargeable battery
AC adapter included
Portable handheld design
Simple one-button use
4.2Editor score
Presidium Multi Tester III
Multi-viewing LED display
Thinnest 0.6mm probe
Tests diamonds moissanites
Carrying case included
3.7Editor score
1. Valkynos Professional Diamond Tester Pen – Best Overall Diamond Tester
Valkynos Professional Diamond Tester Pen
365nm UV light included
Fast 0.5s detection
Portable protective case
Requires bare hands
The Valkynos Professional Diamond Tester Pen stands out as a top choice for verifying gemstones quickly and accurately. With a 4.3-star rating, users appreciate its combination of thermal conductivity and UV light features.
Pros
- Built-in UV for fluorescence
- Very fast detection time
- Compact and portable
- Clear LED feedback
- Includes battery and pouch
Cons
- Needs warm-up period
- Not for metal testing
We may earn a commission when you buy through this link, at no additional cost to you.
Its standout feature is the built-in 365nm UV light which helps detect fluorescence patterns specific to real diamonds. The thermal sensor provides instant 0.5s responses after a short warm-up, making it efficient for high-volume checks.
The device requires bare hands for accurate readings and functions best at room temperature. It may not distinguish all lab-grown diamonds from natural ones without additional tools.
This pen is ideal for jewelers, collectors, and sellers who need a reliable portable tool. Its protective case and included accessories make it ready for travel or everyday use.
Fast and Accurate Detection
The thermal sensor identifies diamonds from simulants in half a second, saving valuable time during transactions or appraisals.
UV Fluorescence Feature
The 365nm UV light reveals unique fluorescence reactions that help confirm authenticity beyond thermal conductivity alone.
We may earn a commission when you buy through this link, at no additional cost to you.
2. Siziviki Diamond Tester Pen Pro – Best Budget Diamond Tester
Siziviki Diamond Tester Pen Pro
LED light indicator system
Requires 30s preheat
Adjustable calibration knob
9V battery included
The Siziviki Diamond Tester Pen Pro offers solid performance at a budget-friendly price. With a 4.1-star rating, it appeals to beginners and casual users who want reliable results without high costs.
Pros
- Affordable price point
- Detailed LED feedback
- Includes user video guide
- Simple operation steps
- Lightweight design
Cons
- Longer warm-up time
- Sensitive to cold conditions
We may earn a commission when you buy through this link, at no additional cost to you.
Its multi-level LED system distinguishes between diamonds, moissanite, jade, and glass. A critical step is the mandatory 30-second preheat and calibration to the fourth mark before testing.
Cold temperatures or windy conditions can affect accuracy, so indoor testing is recommended. Proper battery installation and following the included video guide help ensure correct usage.
This pen is a great entry-level tool for hobbyists or small jewelry shops. It provides essential verification features while remaining easy to carry and use daily.
Clear Multi-Level Indicators
The LED lights provide different signals for various gemstones, allowing users to identify potential simulants quickly.
Comprehensive User Support
A included step-by-step video guide helps users master calibration and testing procedures to avoid common mistakes.
We may earn a commission when you buy through this link, at no additional cost to you.
3. Diamond Selector II – Best Reliable Diamond Tester
Diamond Selector II
LCD display and LEDs
Audible sound alerts
Bare hands required
Leather pouch case
The Diamond Selector II is a classic professional tool known for its straightforward operation. With a 4.0-star rating, it serves well for quick checks in jewelry stores or home collections.
Pros
- Simple LCD interface
- Audible sound feedback
- Includes leather case
- Easy for novices
- Lightweight and portable
Cons
- Must use bare hands
- Not for metal testing
We may earn a commission when you buy through this link, at no additional cost to you.
Its LCD display and LED indicators show results clearly, while audible beeps confirm diamond detection. However, users must operate it with bare hands to maintain proper conductivity.
Cold batteries below 10 degrees Celsius can reduce performance. It is designed strictly for gemstones, not metals, which may confuse new users if they test the wrong materials.
This tool fits jewelers and collectors who need a basic but reliable tester. The included leather pouch ensures protection during storage or transport.
Visual and Audio Feedback
The combination of LCD readouts and beeping sounds ensures users can quickly confirm diamond status without confusion.
Durable Storage Option
The included leather pouch case provides safe storage that keeps the device protected from scratches or damage.
We may earn a commission when you buy through this link, at no additional cost to you.
4. Presidium Instruments Gem Tester II – Best Premium Diamond Tester
Presidium Instruments Gem Tester II
Analog dial display
Self calibration feature
16 gemstone types
Retractable probe tip
The Presidium Instruments Gem Tester II represents a professional-grade option for serious gemstone analysis. With a 4.2-star rating, it is trusted by industry experts for its consistent results and calibration tools.
Pros
- Assisted thermal calibration
- Differentiates 16 gemstones
- Thinnest retractable probe
- Industry trusted reliability
- Compact and sturdy
Cons
- Higher price point
- Calibration may shift
We may earn a commission when you buy through this link, at no additional cost to you.
Its Assisted Thermal Calibration helps adjust to environmental changes automatically. The device can identify 16 different gemstones, distinguishing diamond, moissanite, and common simulants easily.
The probe tip is notably thin and retractable, protecting the gemstone and ensuring accurate contact. However, shipping impacts can sometimes affect initial calibration, requiring support from the seller.
This tester is ideal for jewelers who need precise identification beyond standard diamond checks. Its sturdy build and analog dial offer reliable use in professional settings.
Advanced Thermal Calibration
The ATC feature allows users to self-calibrate quickly, ensuring accuracy despite temperature fluctuations in testing environments.
Precision Probe Design
The thinnest retractable probe tip minimizes risk to delicate stones while providing consistent pressure for reliable readings.
We may earn a commission when you buy through this link, at no additional cost to you.
5. Professional Tester Pen UV – Best Dual-Sensor Diamond Tester
Professional Tester Pen UV
365nm UV light
0.5s instant response
Includes tweezers
9V battery included
This Professional Tester Pen UV combines thermal conductivity with UV light to provide layered verification. Its 4.3-star rating reflects satisfaction from users who value quick and thorough checks.
Pros
- Combined UV thermal tests
- Fast response time
- Includes tweezers
- Clear LED signals
- Ideal for pawn shops
Cons
- Requires warm-up time
- Bare hands necessary
We may earn a commission when you buy through this link, at no additional cost to you.
After a 25-second warm-up, the tester delivers 0.5s responses. The UV light helps screen moissanite and fakes by detecting unique fluorescence reactions that thermal tests alone might miss.
It includes tweezers for handling stones safely during testing. Like other pens, it requires bare hands and room temperatures for optimal accuracy.
Pawn brokers and retail jewelers find this tool practical for daily screening. The added UV capability makes it superior for distinguishing between various simulants effectively.
UV Light Advantage
The integrated 365nm UV light acts as a critical second layer to verify authenticity when thermal results are ambiguous.
Rapid Response Capability
With half a second detection time, users can process high volumes of items quickly without sacrificing reliability.
We may earn a commission when you buy through this link, at no additional cost to you.
6. HMKIS Diamond Tester – Best Value Diamond Tester
HMKIS Diamond Tester
Type-C power option
Includes 60X loupe
LCD display unit
Non-rechargeable design
The HMKIS Diamond Tester Pen offers unique flexibility with a Type-C power option alongside standard battery use. With a 4.0-star rating, it appeals to users wanting stable voltage for better accuracy.
Pros
- Type-C power supply
- Includes 60X loupe
- User-friendly LCD
- Clear audible signals
- Stable voltage output
Cons
- Non-rechargeable battery
- Requires size selection
We may earn a commission when you buy through this link, at no additional cost to you.
Its design includes an LED Jewelers Loupe for visual inspection alongside thermal testing. Users must select stone size beforehand to ensure correct reading results.
The non-rechargeable design is noted clearly to avoid confusion. Proper contact and alignment are critical to avoid incorrect readings or flashing lights.
This pen suits hobbyists who also need a loupe for detailed examination. The power options provide convenience, making it versatile for different testing scenarios.
Power Supply Flexibility
The Type-C power option ensures stable voltage for higher precision compared to standard battery-only devices.
Included Loupe Accessory
The 60X Jewelers Loupe allows users to inspect inclusions and cuts for a comprehensive assessment of gem quality.
We may earn a commission when you buy through this link, at no additional cost to you.
7. GemOro UltraTester 3+ – Best Multi-Function Diamond Tester
GemOro UltraTester 3+
4-way color testing
UV moissanite tech
Rechargeable batteries
Includes carrying case
The GemOro UltraTester 3+ is a professional machine designed for identifying multiple gem types at once. With a 3.8-star rating, it offers solid features for specific verification needs.
Pros
- Color-coded LED results
- Rechargeable battery pack
- Portable and durable
- Identifies sapphire crystals
- Includes full kit
Cons
- Not for lab-grown
- Lower rating than others
We may earn a commission when you buy through this link, at no additional cost to you.
Its color-coded system uses LEDs to show diamond in green, moissanite in blue, and sapphire in pink. UV technology helps detect a wide range of moissanites including low-conductive ones.
It includes a full testing kit with a carrying case and rechargeable batteries. However, it is not intended for lab-grown diamonds which limits some modern use cases.
Jewelers needing multi-type identification may find this machine useful. Its ergonomic design and durable housing make it convenient for frequent professional handling.
Color-Coded Visual Feedback
The LED color system instantly identifies gem types like diamond, moissanite, and sapphire without needing to interpret complex readings.
Rechargeable Power Source
The included rechargeable batteries ensure long usage sessions without needing constant battery replacements.
We may earn a commission when you buy through this link, at no additional cost to you.
8. Purity Testing Kit – Best All-in-One Diamond Tester
Purity Testing Kit
Gold silver platinum kit
Diamond tester included
Touchstone for testing
Acid neutralizer bonus
The Purity Testing Kit is an all-in-one solution that verifies diamonds alongside gold silver and platinum. With a 4.3-star rating, it is highly valued by investors and collectors.
Pros
- All-in-one jewelry kit
- Digital diamond tester
- Safe testing touchstone
- Neutralizer included
- Great for investors
Cons
- Multiple tools required
- Learning curve involved
We may earn a commission when you buy through this link, at no additional cost to you.
It includes a digital diamond tester plus a touchstone to test metals without damaging jewelry. The kit also provides an acid neutralizer to clean stones after testing safely.
While highly versatile, using multiple tools requires following correct procedures to avoid errors. The triplet magnifier helps read results on the touchstone effectively.
This kit is ideal for anyone investing in precious metals and stones. It provides comprehensive appraisal capabilities in a single convenient package.
Comprehensive Metal Testing
The safe testing touchstone determines the karat of gold, silver, and platinum without damaging the jewelry being tested.
Complete Cleaning Tools
The included acid neutralizer quickly cleans stones after testing to ensure they remain pristine for sale or display.
We may earn a commission when you buy through this link, at no additional cost to you.
9. Presidium Diamond Mate C – Best Portable Diamond Tester
Presidium Diamond Mate C
Rechargeable battery
AC adapter included
Portable handheld design
Simple one-button use
The Presidium Diamond Mate C offers cordless convenience with a built-in rechargeable battery and AC adapter. With a 4.2-star rating, it is a trusted tool for professionals who need reliable on-the-spot results.
Pros
- Built-in rechargeable battery
- Simple one-button use
- Compact lightweight design
- Clear LED indicators
- Ideal for field work
Cons
- Requires AC adapter for continuous use
- Basic thermal only
We may earn a commission when you buy through this link, at no additional cost to you.
Its one-button operation with clear LED indicators simplifies testing for both experts and beginners. The lightweight handheld design fits easily in travel kits for estate sales or trade shows.
This unit focuses purely on thermal conductivity for diamond verification. While efficient, it may not distinguish all simulants without additional features like UV lights.
Jewelers and appraisers find this tester efficient for routine checks. The rechargeable feature ensures it remains operational throughout busy days without battery changes.
Convenient Rechargeable Power
The built-in battery allows cordless operation while the AC adapter ensures continuous use without downtime.
Simplified One-Button Operation
With simple controls, users can quickly verify diamond status without navigating complex settings or calibration steps.
We may earn a commission when you buy through this link, at no additional cost to you.
10. Presidium Multi Tester III – Best Versatile Diamond Tester
Presidium Multi Tester III
Tests colorless diamonds
Tests moissanites too
Thinnest 0.6mm probe
Multi-viewing LED display
The Presidium Multi Tester III is the world's first instrument testing both diamonds and moissanites in one device. With a 3.7-star rating, it offers unique versatility for specific identification needs.
Pros
- Tests diamonds moissanites
- Ergonomic anti-slip grip
- 180-degree display
- Tests 0.02ct stones
- Portable with case
Cons
- Requires calibration prior use
- Lower average rating
We may earn a commission when you buy through this link, at no additional cost to you.
Its thin 0.6mm retractable probe can test stones as small as 0.02ct. The multi-viewing LED display is convenient for both right and left-handed users.
Calibration is required before use, which may need support from the seller if issues arise. However, once calibrated, it provides consistent results across different gem types.
This tool suits jewelers who deal with moissanite alongside diamonds frequently. Its ergonomic design and included case make it practical for mobile testing scenarios.
Dual Diamond Moissanite Testing
This is the world's first instrument capable of testing both colorless diamonds and moissanites in a single device.
Ergonomic and Compact Design
The anti-slip grip and portable size make it easy to handle for extended periods without fatigue.
We may earn a commission when you buy through this link, at no additional cost to you.
Buying Guide – How to Choose the Best Diamond Tester
Selecting the right Diamond Tester depends on your needs experience level and budget. Consider these factors to find a model that suits your specific requirements.
Type of Testing Technology
Most Diamond Testers use thermal conductivity to differentiate diamonds from simulants like glass or cubic zirconia. Some models add UV light to detect fluorescence which provides an extra layer of verification. If you deal with moissanite or lab-grown stones, look for advanced testers that distinguish between these materials specifically.
Choose thermal-only models for basic checks and combined UV thermal models for higher accuracy in diverse collections.
Response Time and Warm-up
Faster response times improve efficiency when testing multiple stones. High-end models may offer instant detection while budget pens require short preheating periods. Ensure the device warms up quickly to avoid waiting during busy appraisals or sales.
Prioritize models with under 30-second warm-up times if you need to test many items consecutively.
Display and Feedback Style
Feedback comes as visual LEDs, analog dials, or LCD screens. Visual feedback like beeps or color-coded LEDs help confirm results quickly. Analog dials offer continuous reading which some professionals prefer for precise thermal analysis.
Pick a display style that matches your comfort level and reading preferences during testing.
Portability and Build Quality
Portable testers are essential for jewelers who work outside fixed locations like estate sales or home visits. Look for devices with carrying cases protective tips or ergonomic grips. A sturdy build ensures longevity despite frequent handling.
Choose a compact model with a case if you travel often or store it securely after each use.
Battery Power and Rechargeability
Some testers run on disposable batteries like 9V while others have rechargeable units with AC adapters. Rechargeable models reduce long-term costs and environmental waste. Consider how often you test and whether continuous operation is necessary.
Select rechargeable batteries for professional daily use and disposable for occasional hobbyist needs.
Ease of Use and Calibration
User-friendly devices with simple steps reduce errors during testing. Calibration features help adjust the device to environmental conditions but may require time to set up. Avoid overly complex models if you are new to gemstone verification.
Opt for tools with clear instructions and intuitive controls to maintain consistent accuracy without frustration.
Included Accessories and Support
Accessories like tweezers test platforms or loupe accessories enhance functionality. Manufacturer support such as video guides or warranty service improves the overall experience. Check what comes in the box to ensure you have everything needed to start.
Choose kits that include essential tools like cases and manuals to avoid buying extra items later.
Accuracy and User Feedback
Read reviews to understand real-world accuracy and reliability. Users often point out issues like metal detection false positives or temperature sensitivity. High ratings usually indicate consistent performance but verify specific use cases before buying.
Prioritize models with strong user feedback regarding accuracy for your particular testing scenarios.
How to Use and Care for Your Diamond Tester
Turn on the tester and allow it to warm up as instructed. Ensure the probe is clean and aligned perpendicular to the gemstone surface.
Place the gemstone on a stable surface and use bare hands to hold the unit. Press the probe lightly against the stone and wait for the LED or sound signal.
After testing, turn off the device to conserve power. Store it in its protective case away from moisture extreme temperatures or direct sunlight.
Frequently Asked Questions
Can a Diamond Tester identify lab-grown diamonds?
Standard thermal testers generally cannot distinguish lab-grown diamonds from natural ones because they share similar physical properties. You need specialized equipment or a certified lab report to verify the origin of the diamond accurately.
Do Diamond Testers work on metal or gold?
No, Diamond Testers are designed for gemstones and will not identify metals like gold or platinum. Metal has similar thermal conductivity to diamonds so it may trigger false positives during testing.
Why do I need to use bare hands when testing?
Bare hands ensure proper electrical conductivity which is necessary for the tester to function correctly. Gloves or moisture can block this signal leading to inaccurate results.
How often should I calibrate my Diamond Tester?
Calibrate your device before each use or whenever you move it to a new environment. Temperature and humidity changes affect performance so regular calibration ensures consistent accuracy.
What if the tester beeps when testing a metal item?
A beep during metal testing is normal because metal conducts heat similarly to diamonds. This does not indicate a defect but shows the tool is working as designed for conductivity.
Can I use the tester on loose stones or just jewelry?
Both loose stones and jewelry are suitable for testing. Ensure the stone is clean and has good contact with the probe tip for reliable results.
What is the smallest carat size the tester can detect?
Most Diamond Testers can accurately detect stones as small as 0.02 carats. Stones smaller than this may require alternative methods for verification.
How long does the battery last in these testers?
Battery life varies by model but typically lasts several months with regular use. Rechargeable units provide longer operation between charges for professional applications.
Final Thoughts on Choosing the Best Diamond Tester
We reviewed ten top Diamond Tester models ranging from affordable pens to professional devices. The Valkynos Professional Pen leads with UV thermal features while the Siziviki offers the best budget option.
Prioritize accuracy portability and ease of use when selecting your tool. If you deal with diverse gemstones, choose a model with advanced calibration and multiple testing modes.
Always verify current product details and features before purchasing since models update frequently over time. A reliable tester ensures confidence in every gemstone transaction you make.