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Instructions for M18A9 Electronic Gold Tester

Step-By-Step Directions

  1. Turn power switch up for yellow gold, or down for white gold testing.

  2. Dispense exactly 1 drop of the Activator solution into the Test Well.

  3. Dispense exactly 3 drops of the Electrolyte into the Test Well.

  4. If required, carefully clean test gold with gray eraser at the area to be immersed in the Test Well.

  5. Attach alligator clip lead to the gold you are testing.

  6. Carefully immerse enough of the test gold into the liquid to start the ''Testing" light. Do not touch the reference gold at the bottom of the Test Well and do not touch the alligator clip to the liquid. (Note: Clip must be thoroughly cleaned and dried after any accidental immersion into the liquid.)

  7. Hold the test gold in the liquid without moving for about 2 seconds (until reading on the karat indicators is obtained). To steady your hand, it€™s best to brace a part of your hand on the M-18A or the same surface as the M-1 8A rests on and also, when possible, brace the test gold on the inside of the Test Well just under the surface of the liquid. Be very careful not to touch the reference gold at the bottom of the Test Well.

    Note: To ensure a reliable result, it is important that the test gold not be moved about in the electrolyte after the test has started, until a reading is obtained.
  8. When Karat indicator lights go on, (Testing light will go out) remove the test gold from the liquid and read from the Karat indicator display "bar graph" the highest value which is lit at this time. The display will automatically reset and be ready for the next test.

  9. After the test, use a paper towel or other disposable soft absorbent item to wipe the area of the test gold which was immersed in the liquid as soon as possible after each use. Also absorb the liquid from the Test Well and safely discard when finished testing or in 5 minutes. If the liquid is allowed to stay on the test gold for an extended time, it may tend to discolor the test gold slightly. This can be removed with the Eraser or by almost any jewelry brightening product.

    Important: Do not allow any chemicals to enter the opening around the switch; this may damage the unit and void the warranty.

Please read warning on bottle labels and the following before performing any tests:

The "ACTIVATOR" is a peroxide similar to peroxides used in the home but stronger. If contaminated (i.e. drops dispensed and then drawn back into bottle) Peroxide will gradually release oxygen under pressure. If contamination such as described above, or any other contamination occurs, you must then safely dispose of Activator. Do not retain a contaminated Activator bottle. Replacement bottle(s) of Activator are available (separately from 2-part kits), from Shor.

Dos and Don'ts


Do: occasionally clean reference gold at the bottom of the Test Well with eraser pencil, especially if you suspect any test error.

Do: clean test gold, if necessary, before testing. Unclean gold may result in inaccurate readings. In any case, do clean gold before re-testing in the same area.

Do: keep gold chains very tight (link to link) during testing. Use the fewest number of links (one if possible) between the alligator clip lead and the Gold link to be immersed into the liquid. Three problems can exist with testing chains. (1 ) There may be dirt or contamination between links that would require intensive cleaning (i.e. ultrasonic) before testing. (2) Some chains, especially certain European manufactured chains have a thin non-metallic coating that must be removed before testing that area. The eraser pencil may be used to remove this coating. (3) When testing chains, remember that the solder often used at the link(s) is of a lower karat than the rest of the chain. Therefore, avoid testing in that area.

Do: make sure good contact is achieved between the test gold and the alligator clip lead. If the object to be tested is too large to fit in the clip lead, simply hold the clip lead tightly against the test gold during test.

Do: always clean the test Gold surface with eraser before any repeat testing.

Do: replace the Electrolyte and Activator kit every 18 months.


Do NOT: use chemicals for more than 5 minutes. Once chemicals are dispensed in the Test Well, they may be used for multiple testing for a period of up to 5 minutes.

Do NOT: touch test gold or alligator clip lead to reference gold at bottom of Test Well. If this happens, stop and remove liquid; carefully clean reference gold at the bottom of the Well with the eraser pencil provided, until a normal reading for known gold standard returns.

Do NOT: let alligator clip touch liquid.

Do NOT: leave liquid in Test Well. Do clean after each test or 5 minutes.

Testing For Gold Plate

Probably most of the gold plated items referred to as "costume jewelry" or "fashion jewelry" contain gold at the surface which is no thicker than eight millionths of an inch. Such a gold plate is referred to as gold flash. A large percentage of Gold flash is sufficiently thin and/or porous (microscopically) that the M-18A Gold Tester will "read through" the plate and indicate ''NOT GOLD''. A thicker plate will read as karat gold unless a portion of the surface being tested is erased with the eraser pencil or filed to expose the metal underneath. The eraser should be used as first choice since it is easier to use and non-destructive. However, the eraser will not work on thick gold plate.

To determine that an item is gold plated "non-gold", you must take at least two different readings, one reading of a surface which has not been erased or filed. The reading of the erased or filed surface will be lower if the metal underneath is not gold. (To be sure the metal underneath is not palladium, see the section on "TESTING FOR PALLADIUM"). The M-18A Gold Tester show a ready of "NOT GOLD" if a sufficient area of non-gold is exposed to the liquid. However, the unerased or unfired gold plate exposed to the liquid does have some effect on the reading; so be sure to read point 2 of the following section under "Precautions".

When testing for heavy Gold plate, it may be necessary to use a fast drying lacquer* or material such as a clear fingernail polish. The area to be tested must be coated with the lacquer and allowed to dry. Next make a file mark in the center of the coating deep enough to expose the base metal. Then test the exposed base metal with the M18A9 Gold Tester. Do not allow the electrolyte to touch any part of the gold that has not been coated.

* A fast drying coating liquid, file, and applicator are available with the optional carrying case for the M18A9 Gold Tester.


  1. When testing the unerased or unfired portion, be sure that the test area has been relatively unaffected by wear. flat or thin gold plated items will tend to be worn at the edges. If it is difficult not to expose a worn area when testing an unerased or unfired area, the user may wish to selectively mask any area in question with fast drying lacquer. The reason for masking a worn surface is that if you test a worn surface first, you may obtain the lower karat reading before any erasing or filing has been accomplished. You therefore may not get a lower karat value on your second test and not be able to determine that you are testing gold plate.

  2. When testing the erased or filed portion, be sure that enough of the surface area immersed in the liquid is erased or filed down to expose the suspected "base metal" underneath.

  3. The same Electrolyte can be used for the two comparisons, (the unerased or unfired area test and the erased or filed area test).

Final Point

It is strongly recommended that users of the M-1 8A Gold Tester practice testing for gold plate on a few items believed or known to be Gold plated. A few sets of practice runs will impart confidence to the point that the user will find testing for gold plate to be fast and easy.

Gold Composition

There are four basic colors of gold:

  1. Yellow

  2. White, second most common

  3. Red (Pink/Rose). uncommon

  4. Green. least common

The colors are obtained by the use of two or more varied quantities of base metals. These base metals are silver, copper, zinc and nickel.

Not only are there four basic colors, but each color can and does vary the percentages of the base metals. As such, there is no specific formula for each color of gold. This makes for a range of readings in each color, plus a variation in each color at any specific karat mixture.

The M-18A Gold Tester can distinguish between karats of the two popular colors, yellow and white by means of a color selector switch. Most red colored golds can be determined by using the white range selector position. Most green colored golds can be determined by using the yellow range selector position. There are no ranges that are compatible for use on dental gold alloys.

Caution: The M18A9 Gold Tester is a highly accurate, precision instrument for determining gold karat values. However, should any disagreement arise with its use, it is recommended that confirmation be obtained with a fire assay examination process. This device, although highly accurate, should be used as a guide to gold karat values. The exactness of the device depends on adherence to the instructions provided in this manual and the knowledge of the base metal alloys that are involved.

Testing For Palladium

Both palladium and platinum will indicate karat gold if tested. Platinum jewelry is usually traded at a higher price than gold jewelry, so platinum is seldom marked as gold. Palladium, however, is one-quarter to one-third the price of pure gold, so it should be noted that pure palladium may read as medium karat gold. Palladium prong settings are sometimes soldered into diamond solitaire white gold rings. If palladium is suspected, it is easily distinguished from gold. Nitric acid will quickly turn palladium dark. Gold is not affected in this way.

Table of Standards

Karat Gold Decimal Percentage Gold count (parts per thousand)
18k .750 75.0 750
14k .583 58.3 583
12k .500 50.0 500
10k .417 41.7 417
8k .333 33.3 333

Maintenance of M18A9

No maintenance is required.'

When the "Low Battery" indicator lights, it is necessary to replace the batteries before operating the unit. Simply remove the 4 small screws located on the rear of the Gold Tester. Carefully remove the rear cover. Locate the three "M" batteries and with a small flat blade screwdriver, remove them. Then install 3 new "M" batteries being very careful to observe the correct polarity as shown on the battery holder. Replace the rear cover, being very careful not to pinch the wire leads with the cover. If the batteries are installed incorrectly, the warranty is void and damage may result.

Troubleshooting Guide

Problem Cause/Solution

The testing light does not light.

"Yellow Gold" or "White Gold" light does not light.

Low battery light is on

Replace batteries observing polarity on holder
8 Karat indication for all tests.

Clean test Gold in area to be tested. Alligator clip not connected to test Gold. Reference Gold coated. Reference Gold being shorted by a previous test could result in a film deposit on the reference Gold which must be removed by the eraser pencil see note.

Test gold removed before testing light goes out. Test gold or clip being shorted to reference gold at bottom of Well.

NOT GOLD reading for all tests Alligator clip in liquid during test
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