The Easy Way To Test Gold & Platinum Jewelry
Measure the purity of rings, chains, watches and moreā€¦


So now that you’ve found your fortune detecting – how much is it worth?

That’s the potential dilemma facing every successful detectorist – you may know a friendly reputable jeweller who pays ‘top dollar’ for your treasure finds, or do you take your chances at the nearest unknown pawn shop?

While golden treasure may be instantly recognisable as soon as you uncover it, the gold karat purity rating could be anything from 9K to 24K and that dirty silver ring could even be platinum in disguise!

With the PRO-ALLOY gold tester there’s no messing around with dangerous acids or having to scrape away a portion of your find and potentially damage its intrinsic value. Just place your item on the test plate, touch it with the attached probe, and determine its gold purity from the easy-to-read scale.
PRO-ALLOY is battery powered, so you can use it at home or take it detecting and cash in your finds on the way home!

  • Instant gold karat reading
  • Fast and accurate
  • Non-destructive
  • Protective case included
  • Batteries included (1xAA)

What's included

  • PRO-ALLOY meter
  • Test probe set
  • 1 x AA battery
  • Protective meter cover
  • Soft carry case
  • Multi-language instructions

From the Expert…

With all the different jewellery hallmarks these days it can be confusing trying to work out the quality of your treasure finds, but I recently started using the PRO-ALLOY Gold Tester which removed all of the guess work. It's simple to use and gives peace of mind!

Mark Williams
Detectorist and Blogger

Finds from Minelab users: Valuable finds or costume jewellery?

Gold Karat Ratings

Jewelry will often carry a hallmark or stamp to denote what it is made of and it's purity. Jewelry is sometimes stamped incorrectly, so be ahead of the game and double check your finds before you sell them!

The graph shows some common gold karats, their hallmark and corresponding gold purity (fineness).

Some jewelry is constructed from different alloys, and this might not be visually obvious. E.g, the claws holding a gemstone might be 9K gold whilst the band is 18K. PRO-ALLOY can test the different parts of a single item to help identify their karat ratings.

Karat Hallmark Purity  (Fineness)


24K 999 99.99%
23K 959 95.80%
22K 916 91.60%
21K 875 87.50%
18K 750 75.00%
14K 585 58.50%
9K 375 37.50%

Colored Gold Alloys

18 karat gold is not always the same color. Below are elements that are commonly used in gold alloys, and color types to look out for.*

Gold, normally yellow, can be alloyed with additional elements to alter its color. If you've found something that looks fake, it pays to check it anyway as it could contain gold.

Gold + Palladium = White Gold  
+ Nickel = Grey Gold  
+ Copper = Rose Gold  
+ Silver = Green Gold  
+ Aluminium = Purple Gold  
+ Iron = Blue Gold  



Test Probe Replacement

The test probe supplied with the PRO-ALLOY is a consumable part that will need to be replaced.
A new probe is only necessary after several months if it's used frequently, or if the probe cap is left loose or off.

If the pen has reached the end of its useful life, the unit will most likely behave with similar symptoms of a low battery. While attempting to calibrate on 18K, you will not be able to adjust the needle up (or down) to the 18K mark. If you ever experiences this, try the following:

  1. Make sure that the 18K sample is absolutely clean.
  2. Change battery to a fresh one to see if the problem disappears. We recommend alkaline batteries as they hold a flatter and more consistent discharge curve.
  3. If the two above points do not fix the problem, check the probe for a dry tip or other irregularities.

Replacement Probe Part Number: 3011-0309

Replacement PRO-ALLOY cables (Part No. 3011-0310) and a Protective Meter Cover (Part No. 3011-0311) are available for individual sale.


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