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    GS-24™ Gold Tester Instructions


    GoldStar-24 (GS-24™) is a computerized instrument developed for the quick testing and accurate determination of gold karat values. It is programmed to test values of yellow, white, red and green gold ranging from 5 karats to 24 karats. It tests and determines gold plated, gold-filled materials and base metals and defines them as "NOT GOLD". In addition to the different types of gold, GoldStar-24™ also tests and identifies objects made of Platinum and Palladium.

    The Gold Star-24™ digital unit is a computerized controller that utilizes a newly patented, ST proprietary electrochemical method to obtain an analog signal and convert it to a digital. The unit then processes the converted signal and the final results are displayed on an alphanumeric LCD in both, American and European Standards.


    1. Carrying case
    2. Digital unit
    3. Test probe
    4. Wire harness
    5. Testing plate with an alligator clip
    6. Electrolyte plastic dispensers
    7. Red eraser
    8. Cleaning tissue
    9. Optional AC/DC converter (110/220V)
    1. Digital unit
    2. Alpha-numeric display
    3. Gold color selection buttons
    4. Low battery indicator
    5. Test probe outlet
    6. AC / DC converter outlet
    7. On / Off switch
    Note: When using AC / DC converter, the power switch must be in Off position.

    Chart of Gold Values as Displayed by the GS-24

    Yellow Red White Green
    American European American European American European American European
    5K 208 5K 208 5K 208 5K 208
    6K 250 6K 250 6K 250 6K 250
    7K 291 7K 291 7K 291 7K 291
    8K 333 8K 333 8K 333 8K 333
    9K 375 9K 375 9K 375 9K 375
    10K 416 10K 416 10K 416 10K 416
    111K 458 11K 458 11K 458 11K 458
    12K 500 12K 500 12K 500 12K 500
    14K 585 14K 585 14K 585 14K 585
    15K 625 15K 625 15K 625 15K 625
    16K 666 16K 666 16K 666 16K 666
    17K 708 17K 708 17K 708 17K 708
    18K 750 18K 750 18K 750 18K 750
    -- -- -- -- 20-22K 833-816 -- --
    21K 875 21K 875 -- -- 21K 875
    22K 916 22K 916 -- -- -- 916
    24K 999 -- -- -- -- -- --
    Note about Colored Gold: In the jewelry industry, the common standards dictate that there are four colors of gold: yellow, white, red and green. This is determined by the ratio of silver, copper and other alloys, that is contained in the gold. Alloys of yellow gold contain silver and copper in the ratio of correspondence of 2:1 to 1:2. Alloys of red (pink) gold contain less than 5% of silver, and 1% to 5% zinc; the rest is copper. Alloys of green gold contain over 80% silver, the rest are copper and zinc. Alloys of white gold contain from 18% to 23% nickel, less than 5% silver and zinc.


    1. Plastic cover
    2. Plunger
    3. Platinum electrode
    4. Connecting wire from platinum electrode (3) to connector (5)
    5. Test probe connecting outlet
    6. Push-button
    7. Spring
    8. Plastic dispenser with electrolyte

    Operating Procedures - Assembly & Wire Connections

    1. Digital unit
    2. Red connecting wire
    3. Black connecting wire
    4. Testing plate
    5. Test probe
    6. Digital unit connecting outlet
    7. Alligator clip
    8. Test probe connecting outlet
    9. Gold sample / article to be tested

    12 Steps to Successful Gold Testing

    1. Connect black wire (3) to the test probe (5) by inserting it into the test probe connecting outlet (8).
    2. Connect red wire (2) to the alligator clip on the testing plate (4)
    3. Plug dual wire junction (red and black) into the digital unit connecting outlet (6)
    4. Turn digital unit (1) ON by sliding the On / Off switch to On position. (See diagram 1 (7). The unit should display: READY TO TEST
    5. Place testing sample (9) on the testing plate (4) and secure the contact with an alligator clip (7).
    6. Select testing point on the sample close to the alligator clip but make sure that the electrolyte does not touch the alligator clip during the test.7. Before testing, thoroughly clean testing point with an ordinary red eraser (provided), in order to remove oxidation.
    7. Press and hold down push-button (6) of the test probe (diagram 2), and while holding it down. clean the tip of platinum electrode (3) (Diagram 2) with a paper tissue. After 10-15 tests, cleaning of the platinum electrode with a tissue paper damped in rubbing alcohol is recommended.
    8. Release push-button and flip the test probe nozzle shown at right. Fill sensor tip with an electrolyte from the plastic dispenser (2). Make sure that no air bubbles have formed in the portion of electrolyte drop.
    9. Firmly holding test probe straight up with its nozzle down. Place sensor tip filled with an electrolyte onto the previously selected, and eraser cleaned testing point on the sample. Make sure that selected testing point is completely covered by the sensor tip
    10. Test probe
    11. Electrolyte plastic dispenser
    12. Electrolyte drop
    13. While holding the test probe vertically down on the testing point, select and press one of the buttons (2) on the digital unit (1) in accordance with the color of gold that you are currently testing.
    14. The sign "Testing Yellow" or (Red, White, Green) will appear on alpha-numeric LCD indicating that the gold testing process is in progress. After a few seconds of analyzing, Gold Star-24™ will display the final results in both, American and European standards.
    15. The test is now successfully completed Note: Buttons (#2 in the above photo) are “Y” for yellow gold, “R” for red or pink gold, “W” for white gold and “G” for green gold.
    16. After each test thoroughly, clean the sensor tip with a paper tissue by repeating step (8).
    17. Note: Platinum sensor tip is placed on the testing point before it has been filled with electrolyte. or, it testing point has not been thoroughly cleaned with a red eraser or if the air bubbles have formed in the electrolyte drop. the alpha numeric LCD will display a "NO CONTACT" sign. Before further tests are attempted please repeat steps 7 through
    18. Testing Platinum and Palladium
    19. Press (W). White gold testing button on the digital unit.
    20. Proceed with the test in a usual gold testing manner.

    Testing Gold Plated Articles: The sophisticated electronic design of the Gold Star-24™ and its state-of-the-art microprocessor allows the instrument to accurately distinguish the difference between gold-plated, gold-filled and solid gold materials. Electrolyte used by Gold Star-24™ in the gold testing process. Penetrates thickness of the material during the test to an approximate depth of 2.5 microns. As a rule, the correct results are usually achieved the first time (subject to a proper and thorough cleaning of the testing point with a red eraser.)

    Another Method of Testing Gold Plated Articles

    1. Make 2-3 tests on the same sample spot.
    2. Thoroughly clean the testing point with the red eraser after each test.
    3. If the karat of the testing subject decreases after each test. The testing material is not gold.
    4. If there are any doubts about the material that you are testing, or if you suspect that the gold plated or the gold filled layer on the article is thicker than 2.5 microns, or to ensure that the results are correct, carefully sand testing point with a fine file so that the electrolyte penetrates the layer. Repeat testing procedure, steps 7 through 10 (12 steps). If the tested material is gold plated or gold filled the Gold Star-24 will identify it as NOT GOLD. Testing Articles Larger than the Alligator Clip: When testing articles larger than the alligator clip, remove red wire plug from the alligator clip, and while holding it down. firmly press the plugs metal tip against the eraser cleaned testing point, making an electrical contact. Proceed with the test by repeating steps 7 through
    5. Important Notes
    6. During the test, DO NOT push the button on the top of the test probe (sensor).
    7. After the test is finished, push the button of the test probe, and using tissue paper, clean the old electrolyte from the tip of the platinum electrode. After 10-15 tests, it is recommended to clean the platinum electrode with a tissue paper dipped in rubbing alcohol. DO NOT rub the platinum electrode with an eraser.
    8. Before testing, clean up the testing point on the sample with a red eraser to remove oxidation.
    9. Select a testing point on the sample close to the alligator clip, but make sure that the electrolyte does not touch the alligator clip.
    10. Make sure that no air bubbles have formed in the electrolyte drop.
    11. If you are testing on the same spot several times, be sure that the dark point has been removed with a red eraser before each test. If you did not remove the dark point, you can have a different result after each test on the sample.
    12. Make sure that the sensor tip covers the testing point.
    13. Always select testing point close to the alligator clip but do not let electrolyte touch the alligator clip during the test.
    14. It is not recommended to continuously test at the same point. If an additional test must be conducted at the same point, be sure that the surface is thoroughly cleaned after each test with the red eraser.
    15. During the test, the testing point should be completely covered with the tip of the sensor. Before each test, make sure that the electrolyte drop contains no air bubbles.
    16. Do not attempt to open or disassemble digital unit. This will distort the test results and void the warranty.
    17. If after continuous tests the air bubbles start forming in the electrolyte dispenser, slightly shake the dispenser one or two times and continue testing.
    18. The GS-24™ is not recommended for dental gold. The palladium that is contained in dental gold alters the determination of the karatage of gold. The GS-24™ also is not recommended for white gold that contains palladium.

    Troubleshooting Guide for GS-24 GOLD STAR/Tester

    If the instrument continuously displays: NO CONTACT
    1. Check to see if all of the wires are properly connected.
    2. Check the wire harness with an ohmmeter and replace if necessary.
    3. Check and replace the test probe if necessary.
    4. If there is no electric contact between the alligator clip and test sample, secure the contact or replace the alligator clip if necessary.
    5. The tip of the test probe may not have been filled with a full drop of Electrolyte or air bubbles may have formed in the Electrolyte chop.
    6. The testing sample may not be solid (e.g., chains) consisting of several parts there can be no void and test probe must cover and contact the testing point completely. There must be electronic contact between clip and test point.
    7. The test probe is sealed and glued. It must never be opened. Do not twist the button on the top of the probe.
    If the instrument incorrectly displays: NOT GOLD
    1. This may happen if during tossing, the electrolyte accidentally touches the alligator clip.
    2. The button on the top of the test probe was pressed down mistakenly during testing.
    If the instrument displays different results
    1. The GS-24 may not have been in use for a long period of time Perform several tests before obtaining your final reading.
    2. Thoroughly clean the testing point with the red eraser. This must always be done.
    3. Push down on the button of the probe and thoroughly clean the platinum electrode tip with a lint free cloth dampened in rubbing alcohol, or push down the button of the test probe and very gently (do not rub! clean the platinum electrode with the red eraser. Then conduct several tests on 14 K gold.
    4. The testing point (area) may not be fully covered by the Up of the test probe.
    5. The testing point of the sample being tested may not be smooth (uneven).

      The sample to be tested is not of homogeneously mixed gold, thus presenting different karats at different places of the surface.

    Note: If testing the same sample many times after several tests, wash the sample with water to remove old electrolyte.