Reviews of 9 electronic gold testers (and pen-probes)

Last updated: March 25, 2026

IGNOR THIS (HISTORICAL) ARTICLE BUY A CURRENT MODEL, CLICK ON A PICTURE
LEFT Analyzer. RIGHT PRO.

This article reviews several electronic gold testers, including how they compare with using chemical (acid) testers. This is a 'historical' article of discontinued electronic models - but it gives you a good idea of how technology has improved (i.e. get the latest model!)

SUMMARY
COMPARISONS CHART: Analyzer, Pro and KEE
PEN-PROBES
KEE
ELECTRONIC TESTERS OR ACIDS?
RELATED ARTICLES

SUMMARY

Want to buy one now? Skip this article and see our two current models.

** Current model ** The Auracle ANALYZER has the same electronics (microchip) as the KEE tester, giving an almost instant result, just like the KEE, but on an LED scale rather than an analogue meter. And there's a digital display telling you what to do, a nice touch. This is the simplest and most reliable of the two models. See also, extended information, evaluation and reviews.

** Current model ** Auracle PRO is fully digital, one-touch calibration, many features, much more stable than any of the old AGT models (listed below). For product information and to buy, see our product page for the PRO. for or extended information, evaluation and reviews of the PRO.

COMPARISONS CHART: Analyzer, Pro and KEE

The KEE was discontinued in 2025, it had an analogue meter and was very simple - and very reliable. Since the KEE was so well-known and highly-recommended, here's a chart showing how it compared with our two current models.

	Testing range	Display	power	LowBatt indicator	Cal*	Probe life (max)	CE Approved
Auracle Analyzer	8ct – 24ct	LED (carat) LCD (prompts)	Battery Mains	Yes (“low batt”)	18ct	6000 tests	Yes
Auracle Pro	8ct – 24ct	LCD (various modes)	Battery Mains	Yes (percentage)	18ct	6000 tests	Yes
KEE**	8ct – 24ct	Analogue meter	Battery	No	18ct 22ct	3000 tests	No

* To keep these testers working accurately you need to calibrate them against known samples.

** Now discontinued.

PEN-PROBES

For models Auracle ANALYZER and Auracle PRO.

Our ref. for this product is Probe-Auracle, there are other pen-probes that look exactly the same, this one should have a gold sticker - when buying a replacement, check that you are ordering the correct one.

PROS.

Compared with other pen-probes this has by far the longest life. The manufacturers say 'up to 6000 tests' - though that, of course could be any number up to 6000.
Finer tip that the other pen-probes, easier (than with other pen-probes) to test very tiny items.

CONS.

Whenever you start to test items (e.g. when turning the tester on) you must 'prime' the pen-probe by carrying out a couple of tests (and ignoring the results!). This is like 'priming' a pump-dispenser (e.g. with toiletries, cosmetics, cleaners) before it will work. The manufacturers call this, "charging" which is misleading because you do not connect it to a charger.
It's not obvious when you need to replace the pen-probe. Clues: when you calibrate it and it reads, "Out of Range" or if it reads not gold on your calibration sample or if the readings are erratic.

PEN-PROBES FOR KEE

Our ref. for this product is Probe-KEE. There are other pen-probes that look similar, this one has a "KEE" sticker - when buying a replacement, check that you are ordering the correct one

PROS.

No need to 'prime' before use
Well-established (we sold many thousands before the KEE went out of production in October 2025), well-known
Easy to know when you need to replace the pen-probe (when you calibrate it and the knob won't turn far enough to move the needle).

CONS.

Shorter life than other pen-probes (up to 3000 tests). Extensive feedback indicates that this is 'variable' - at worst it will last six weeks, at best 18 months.
It dries up very easily if you don't replace the cap firmly
Thick tip, not so easy to test very small items

PEN PROBES FOR AGT1 & AGT3 MODELS

Our ref. for this product is Probe, there are other pen-probes that look exactly the same, this one should have a silver sticker - when buying replacements, check that you are ordering the correct one. Although the AGT1/AGT3 models were discontinued years ago, the pen-probes are still available, though to special order only, which means delivery is, typically, 3 to 6 weeks. It is likely these pen-probesy will be discontinued in 2027.

KEE

Discontinued in 2025.

The same electronics (in particular the microchip that gets it to work so well) was transferred to the Auracle Analzyer.

PROS, simple design, fast response, the needle on the meter shoots up to the carat marked on the dial; accurate when testing high carats (requires very careful calibration with both and 18ct and a 22ct sample); extra set of leads for testing large items that won't fit on the test plate (though we' heard of anyone to needed to use them).
CONS, no option for a mains power supply, it's battery-only, and no battery level indicator; not reliable for testing platinum, the best you can say of a "platinum" reading is, 'It might be platinum or Palladium"; for testing high-carat gold accurately you have to use two calibration samples and calibrate it very carefully, not 'difficult', just a little fiddly. Awkward to change the battery.

Although the following haven't been made for a few years now (and, therefore, the following information is for 'interest-sake only') we do still sell replacement pen-probes. Replacement pen-probes are usually available for a few years after a model has been discontinued.

AGT MODELS

Not all AGT models are the same!

NOTE: the AGT models were discontinued a few years ago. You can probably still find them secondhand please don't send any to us for repair, they are not repairable.

AGT1 (original model)

Quite OK once you've got the 'feel' for how the row of LED lights shoot up, then keep going up, then slowly go down, and usually settle on a reading...but many people try for a few minutes then give up. Shop staff who don't get proper training and don't have time to 'get the knack' and are under pressure in a busy shop - they will have no chance of getting a meaningful reading.

Each time you switch it on you must calibrate against the 14ct calibration sample, sometimes it doesn't work and you have to calibrate it 2 or 3 times, then you must 'charge' the probe by carrying out a few 'dummy' tests before getting a reliable reading, and all of this takes a couple of minutes. Every few days it has a nervous breakdown and won't work at all, it is not 'broken', you can fix it by calibrating it 6 or 7 times in succession, it's not difficult to do but it is frustrating, especially if you have a queue of customers. Not very accurate at testing high carat.

All this said, my colleague liked this model best of all because, once you'd got the 'knack' of how to take a reading, it was the most accurate of all the AGT1s.

AGT1 Plus

Compared with the AGT1 (original) above, calibration usually works first time, it has nervous breakdowns less often, it 'feels' nicer to use (more responsive). You still have to 'charge' the probe by carrying out a few 'dummy' tests before getting a reliable reading. It's not as frustrating to use as the original AGT1 but there will still be times when calibration doesn't work the first time and you have to calibrate it 3 or 4 or 5 times in succession. You still need to spend time 'getting the feel' of the readings.

AGT1 Deluxe

The full name given by the manufacturer's is AGT1 PLUS DELUXE

The supplier says that the electronics were re-designed and you don't have to 'charge' the probe before use...but they also say that you should charge the probe anyway. We couldn't find any difference between this and the earlier models as regards operation.

AGT2

A pen-probe, a testing plate, a box of electronics (not shown in the manufacturers pictures) and the connecting leads. You connected it to your phone. It was discontinued in 2018. Then they discontinued the app. so that updates on your phone (or if you got a new phone) stopped it working.

AGT3

Fully digital version, new sleek design, one-touch calibration, superseded, in 2025, by a much-upgraded version (same design but better electronics), the Auracle PRO

MIZAR M24

Accuracy. Plus or minus one light, e.g. if it reads 14ct it might be 12ct or it might be 16ct but not this accurate above 18ct. OK if you want to know if an item is "low carat" or, possibly, "high carat" - otherwise, fairly useless. Pros.. very cheap; - very simple, a light for each carat; Mizar make a few models, this is by far the best. Cons. the contact fluid is a strong acid which dissolves the sensor if it is not cleaned meticulously after every use; you need good eyesight and a steady hand to place the test-item into the tiny well that you fill with acid; you can only test tiny items; no mains power option, no way of calibrating it. CONCLUSION. We did once sell this, because there are always customers who must have "the cheapest" - but, in the end, we decided there were just too many complaints. However, if you just want to know if an item (a small item!) contains some gold and aren't bothered about measuring how much, and you are only going to test small items, you will find (as of 2026 anyway) it is still available...but not from us.

ELECTRONIC TESTERS OR ACIDS?

Before deciding on an electronic tester, it's worth considering acids. We speak of, "the acid test' meaning the absolute proof. Safety. The electronic testers we sell do not use acid so they are 'safer'. However, acids are only hazardous if you are 'exposed' to them. 'Exposed' means getting acid on your skin or inside your body. Wear acid-proof gloves (very cheap, we sell them) and don't sniff or drink the acid, then there is no exposure, no risk, no hazard. Accuracy. If you want to test high-carat accurately (e.g. to see the difference between 21ct, 22ct and 23ct) acids are more accurate. Electronic testers are not accurate when testing white gold or platinum and do not test silver, Palladium and steel. Flexibility. Acids can test for silver, white gold, platinum, Palladium and steel. Ease-of-use. Electronic testers are easier but even acids are 'easy to use' once you've tested your first dozen items and have got the hang of it. Consumables. Acid has a shelf life of about a year, but pen-probes (which are filled with a salt solution) also have a shelf life of 10 to 15 months. In both cases, if you do a lot of testing you will use up the fluid in well-less than a year. A bottle of acid costs about £17.00, a pen-probe about £50.00. An analogy: a pen-probe is like an all-in-one ink cartridge, bottles of acid are like individual ink cartridges. Reliability. Modern testers are reliable but any electronic device can break down. If it breaks down within the one-year guarantee period, we replace it; once out of guarantee it is not repairable. A bottle of acid can't break down, you use up the acid, you buy a new bottle. More. See Guide to Chemical Testers.

There are several other methods of testing precious metals, see Twelve methods of testing gold, silver and platinum.

You're not so interested in 'historical' models, you want one now. Which one? See how do the Auracle ANALYZER and Auracle PROs compare?
Not sure what type of tester to get? See our fascinating article, Twelve methods of testing gold, silver and platinum.
For small very fragile/valuable items such as rare coins (and also loose gemstones) see the specific gravity tester.
You have read about the limitations of electronic and need acids to test the precious metals that electronic gold testers can't cope with - see our special Q3 for use with electronic gold testers. Please note, this is only available for sale with electronic gold testers.
Finally, do remember that acids are the most versatile and accurate for testing precious metals, see What he various testing kits do and Testing white metals.