How To Use Diamond Selector II: The Definitive Guide To Precision Gemstone Testing

Successfully operating the Diamond Selector II requires precise calibration of the thermal conductivity probe based on ambient temperature and gemstone carat weight to distinguish between genuine diamonds and common stimulants like Cubic Zirconia. By mastering the 90-degree contact technique and interpreting the multi-stage LED response, users can achieve a 98% accuracy rate in detecting non-diamond materials, provided they account for the tool’s inherent limitations regarding Moissanite.

Essential Pre-Operation Calibration and Equipment Protocol

Before attempting to verify a gemstone, the environment and the device state must meet specific technical criteria. The Diamond Selector II is a thermal conductivity meter; it measures the rate at which heat moves from the probe tip into the material being tested. Because diamonds are peerless thermal conductors, they dissipate heat faster than almost any other material. However, this process is highly sensitive to external variables such as the starting temperature of the probe and the surface cleanliness of the stone.

Initial Setup Requirements and Technical Benchmarks

• Mandatory Hardware: A fresh 9-volt alkaline battery is non-negotiable. Lower voltages from dying batteries lead to "sensitivity drift," where the device provides inconsistent readings or fails to reach the "Ready" state.
• Surface Preparation Tools: Microfiber lint-free cloth and 90% Isopropyl alcohol. Any skin oils or film on the gemstone act as an insulator, potentially causing a diamond to test as a stimulant.
• Testing Environment: Stable room temperature between 18°C and 30°C (65°F - 86°F). Avoid testing directly under air conditioning vents or in high-humidity areas, as moisture on the probe tip creates a thermal bridge that skews results.
• Physical Accessories: The small metal testing tray (usually included) is required for loose stones to ensure the stone is properly grounded and to prevent the user from touching the stone directly, which transfers body heat and ruins the reading.

Step-by-Step Diamond Selector II Operation and Execution

Testing a gemstone is a four-stage process involving power stabilization, sensitivity calibration, physical contact, and data interpretation. Deviating from these steps often results in "false negatives" where a real diamond is misidentified due to improper gain settings.

Step 1: Power Sequencing and Thermal Stabilization

Turn the volume/power dial clockwise until you hear a click. The "Power" LED (usually green) will illuminate. At this stage, the internal heating element in the probe tip is warming up. You must wait for the "Ready" or "Lamp on Ready" light (usually yellow or a secondary green) to glow steadily.

This waiting period typically lasts 20 to 30 seconds. Do not attempt to calibrate the device before the Ready light is active. If you calibrate during the warm-up phase, the sensitivity will drop as the probe continues to heat, leading to inaccurate readings during the actual test.

Step 2: Sensitivity Calibration Based on the Volume Dial

The Diamond Selector II uses a numbered scale (1 through 8) on the display to indicate thermal conductivity levels. You must manually set the "baseline" sensitivity using the volume dial. This setting is dictated by two factors: the size of the stone and the temperature of the room.

1. Identify the carat weight of the stone approximately.
2. Check the ambient temperature of your testing area.
3. Adjust the dial until the level meter shows the specific starting number recommended for those variables (refer to the technical table in the next section).
4. For a standard 0.50-carat stone at room temperature, you will typically adjust the dial until the first 2 segments of the level meter are lit.

Pro-Tip: If you are unsure of the stone's weight, start with a lower sensitivity setting (Level 2). It is safer to re-test with higher sensitivity than to get a false "Diamond" reading because the gain was set too high for a small stone.

Step 3: Executing the Physical Probe Contact

The probe tip is a delicate copper-colored needle. It must be held at a perfect 90-degree angle relative to the facet of the gemstone.

1. Hold the Diamond Selector II like a pen. Your index finger should be resting on the metal conductive plate on the back of the device (if your model features one) to complete the circuit for the "metal alert" buzzer.
2. Gently touch the tip to a flat facet of the stone—ideally the table (the large top facet).
3. Apply only enough pressure to depress the spring-loaded tip slightly. Excessive force can bend the probe or scratch the setting of the jewelry.

Warning: Do not touch the metal setting or the metal testing tray with the probe tip. If you do, the device will emit a continuous "buzzing" sound. This is the metal alert, indicating that the reading is invalid because metal conducts heat/electricity differently than gemstones.

Step 4: Interpreting the LED and Audible Feedback

Once contact is made, the level meter will react instantly.

• Simulant (Glass, CZ, YAG): The level meter will stay at the baseline or only rise 1-2 bars. No audible beep will occur.
• Genuine Diamond: The level meter will rapidly climb into the red zone (Levels 7, 8, or 9). Simultaneously, the device will emit a rapid "beep-beep-beep" sound.
• Moissanite Alert: Note that the Diamond Selector II cannot distinguish between Diamond and Moissanite. Both will trigger the red LEDs and the beep. To differentiate these two, a specialized Moissanite tester (which measures electrical conductivity) is required.

Technical Sensitivity Parameters and Calibration Metrics

The following table provides the standard calibration settings for the Diamond Selector II. "Level" refers to how many bars should be lit on the display before the probe touches the stone.

Note: These levels are foundational. If you are testing in a very humid environment, you may need to reduce the sensitivity by one level to prevent the moisture in the air from causing a "jump" in the thermal reading.

Common Operational Failures and Field Fixes

Even with a high-quality Diamond Selector II, users often encounter errors that lead to misidentification. Understanding the root cause of these failures is essential for maintaining professional-grade accuracy.

• Failure Scenario: Constant Beeping Without Contact

  
  
  
  • Root Cause: The sensitivity (volume dial) is turned up too high, or the device has been left in a very hot environment (like a car), causing the thermal sensor to max out.
  • Actionable Fix: Turn the dial back to zero, turn the device off, and let it sit in a cool, dry area for 10 minutes. Replace the battery if the issue persists, as low voltage often causes "looping" circuits.

• Failure Scenario: No Reaction on a Known Diamond

  
  
  
  • Root Cause: Oxide buildup on the probe tip or a "cold" probe. If the tip is dirty, it cannot transfer heat.
  • Actionable Fix: Clean the probe tip by gently wiping it across a piece of clean white paper or a specialized abrasive cleaning stone designed for testers. Ensure the "Ready" light is fully illuminated before re-testing.

• Failure Scenario: Metal Alert (Buzzing) Triggers on the Stone

  
  
  
  • Root Cause: This occurs when the probe tip slips off the gemstone and touches the prong, or if the stone is so small that the tip overlaps onto the metal setting.
  • Actionable Fix: Use a magnifying loupe to guide the probe tip exactly onto the center of the facet. If testing a very small "melee" diamond, ensure the stone is dry and use a steadying hand rest.

• Failure Scenario: The "Moissanite False Positive"

  
  
  
  • Root Cause: Moissanite has a thermal conductivity profile nearly identical to diamond. The Diamond Selector II is not designed to distinguish between the two.
  • Actionable Fix: Use a secondary testing method, such as a Moissanite Tester (electrical conductivity) or a "Multi-Tester." You can also look for "double refraction" under a 10x loupe, which is a signature of Moissanite but never seen in diamonds.

Frequently Asked Questions

Can the Diamond Selector II test stones that are already set in rings?

Yes, the device is designed to test both loose and mounted stones. When testing mounted stones, you must be extremely careful not to touch the metal prongs or the band, as this will trigger the metal alert buzzer and nullify the reading.

Why does my tester give different results on the same stone?

Inconsistent results are usually caused by the stone heating up. Since the probe transfers heat into the stone, a small stone will become warm after one or two tests. Once warm, it will no longer dissipate heat as effectively, leading to a lower reading. Wait 2-3 minutes for the stone to return to room temperature before re-testing.

Does the Diamond Selector II detect Lab-Grown Diamonds?

Yes, it will identify Lab-Grown Diamonds as "Diamond." This is because Lab-Grown Diamonds are chemically and physically identical to mined diamonds, including their thermal conductivity properties. It will not, however, tell you if the diamond is lab-grown or natural.

How long does a 9V battery last in this device?

Under moderate use, a high-quality alkaline battery will last for approximately 3 to 4 hours of continuous "on" time. Because the heating element in the probe draws significant current, it is recommended to turn the device off immediately after you finish your testing sequence.

Is the Diamond Selector II waterproof or shock-resistant?

No. The probe tip is a highly sensitive electronic component mounted on a delicate spring. Dropping the unit or exposing the probe to moisture can permanently damage the sensor. Always replace the protective plastic cap over the probe when the device is not in use.

Precision Equipment for Gemstone Verification

Equipping yourself with a Diamond Selector II is the first step toward professional-grade jewelry appraisal and fraud prevention. To ensure the highest level of confidence in your results, always pair thermal testing with visual inspection using a 10x achromatic triplet loupe.