How to Test Precious Metals, Jewelry, Coins & More
Why Is This Skill So Valuable?
You don't have to be a precious metal buyer or seller to enjoy the benefits of knowing how to properly test for metal content. Whether you're a rapper who wants some real bling-bling or a guy purchasing his girlfriend some vintage jewelry, knowing how to figure out what it's really made of instead of relying on someone else to tell the truth is very handy! So read on to learn a skill that pays in more ways than one.
What Supplies Do You Need?
First you will need to get some supplies. As amazing as the human eye is, it's hard to tell what is under the surface of any supposed precious metal item simply by looking. So get the tools that will help you get beneath the surface (links to supplies I use/recommend below).
Attract The Right Deals!
A is your 1st line of defense against fakes. Great for when you don't have your acid test kit w/ you in the field. Avoiding magnetic pieces increases your chances of finding precious metals. Don't use a magnet from your refrigerator, they don't have the strength that's needed to accurately determine if something is ferrous or non-ferrous. neodymium rare earth magnet
Get in the Loupe!
Carson loupes are quality, affordable & come from a trusted name in the game. I don't have but I have another standing model of theirs & a vintage no brand that is built like the ol' days. This design (slide) is going to best serve you for investigating possible precious metals. this particular Carson loupe
Get to the Bottom of it!
is the trusted brand I choose to use. Quality control is important when dealing in precious metals as theres lots of money on the table. Don't go cheap and get unreliable acid or test stones. Remember to get new acids about every year or so. I also like the wooden box sold by Puritest to keep your acids contained and fresh. This Puritest acid test kit from JSP
Now that you got your supplies and your ready to learn, let's get started! Don't rely on someone's word, your sight or touch. Master your tools & don't be afraid to whip them out. Better safe than sorry!
1. Magnet: Use your neodymium magnet to run over the piece(s) in question. If there is a magnetic pull, chances are it isn't any precious metal. Though a slightly magnetic piece could indicate a magnetic alloy or a plating. Either way I would steer clear of anything magnetic unless you know it's just base metal. Remember clasps often have magnetic metal springs inside & earring can have magnetic posts.
2. Loupe: Now if it's not magnetic, you can look for metal marks... pull out your loupe now! I personally find it easier to look for marks first, but if your eyes are bad even w/ a loupe you may find yourself squinting. The marks are different depending on where you live or where the piece is from.
- Assuming your from America, the basics for silver are; STER., STERLING, STERLING SILVER, PLATA, .800, .835, .925, .950 & .999. There are more but they are either foreign or rare. For example some other countries use symbols instead of numbers of words.
- The marks for gold most commonly are; 9K, 10K, 14K, 18K, 22K, 24K, 416, 585, 750, 9 KARAT, 10 KARAT, etc. 14K=585 parts gold, 18K=750, etc. Don't confuse karat with carat. Karat is the purity of the gold, while carat is referring to weight, generally of gemstones. Look all over the piece, but generally inside of rings, on clasps, & behind pendants or charms.
- Platinum marks are PLAT, 800, 850, 900 & 999 while Palladium is usually 500, 950 & 999. These metals are rarer then the others & are a little trickier to test.
3. Acid Test Kit: Now as you may have assumed, it is time to whip out the acid testing kit. Inside the kit you will have a test stone & your acids. I suggest a wooden container to keep them somewhat contained and fresh. There are different acids for different supposed precious metals.
- If you think the piece is silver or it had a mark, scratch the piece on the stone hard enough to make a solid mark but not hard enough to damage. If you see a base metal where you scratched the piece then you know it's plated. If not use a drop of the silver acid onto the scratch on the stone. The 18K acid can also be used. Some people prefer that. The silver acid will turn a strong red for sterling and it will stay red, if it gets red then fades away real quick it was plated or you didn't get a good enough scratch. The 18K acid will turn sterling a milky blue while eating away at a fake just like the silver acid. A piece that is less than 925 will be a lighter red, but will still stay.
- For gold there are four acids; 10, 14, 18 & 22. The 22K is good for cleaning the stone when done. To test for gold on a piece you don't want to destroy, no matter the mark, scratch the piece onto the stone just like you would a suspected piece of silver. Then starting w/ the 10 karat acid apply a drop and watch for reaction. If it fades, disappears or smokes it is a fake, under 10 karat or possibly plated w/ something. If it remains repeat w/ 14K acid all the way up to 22K or until it fades away. For example a piece marked 14K that has a scratch that stayed solid w/ 10K acid but disappeared slowly w/ 14, we can assume it is real gold but under karat a bit. Some jewelry is really 12 or 13 when it's marked 14.
- If you are still unsure about the results; you will need to perform a destructive test by either filing deep into the piece or cutting it to get through any potential plating. Many white gold & sterling silver pieces are plated w/ rhodium that can be slightly magnetic & cause uncertain acid test results. So if you are scrapping the piece & can't determine the content then you can resort to the file method or even cut the piece to get all the way through to the center. You would then apply the appropriate acid to the piece and watch for a reaction. If it starts turning green or smoking then you obviously know it's not real. This method is only effective once you have determined the streak test results aren't sure enough.
- Platinum & Palladium are tested very much like gold would be. 22K acid can be used for both but it's recommended to a specific platinum acid if you will test it w/ any regularity. Many metals can give a false positive for platinum so use a magnet and if it's magnetic steer clear no matter what. For palladium on the stone you are looking for the streak to turn very slowly into a yellowish green color instead of fading away. For platinum you want the streak to stay a bright white for a good minute.