HOW TO TEST FOR PRECIOUS METALS
This is detailed information on how to use our test kit in testing for precious metals, and helpful information on doing so. Note: This is copyright and may not be reproduced without permission of Belleair Coins Inc.
Caution
Use extreme care in handling testing solutions as they are corrosive acids. In case of skin contact, flush with large amounts of water. Then treat affected area with sodium bicarbonate (baking soda). If swallowed, contact a physician or hospital at once. In case of spills, treat with water and then sodium bicarbonate, (baking soda).
Following these instructions will not make you an assayer, but it will give you the basic knowledge to become one. Practice and more practice, using the test kit and common sense are the secrets to becoming an expert metals tester. Don’t rely blindly on acid testing. Use your eyes, hands, and head. Observe the color of the gold. Scrutinize the piece. If it looks like junk jewelry and tests to be gold, something may be wrong. Most
karat stamps are correct, but don’t rely completely on all of them.
Think!! After repeated testing you should be able to develop an instinct for the different pieces you will encounter.
Note: Non destructive tests mentioned here mean rubbing a streak of metal on the black stone which will not damage jewelry or other items. Destructive tests mean taking a file or knife and filing or scraping through the surface layer of metal.
HOW TO USE THE TEST KIT
IMPORTANT! Accurate readings will be difficult unless the test stone is thoroughly sanded with #240 to 400 sandpaper provided in the kit. Remove accumulated metal streaks with the same sandpaper.
Breaking in a new gray colored stone: After the stone has been very thoroughly sanded on both sides, take a squirt bottle of 14K acid and cover the entire surface one side at a time. You will see numerous microscopic bubbles as the acid is absorbed into the stone. Set the stone aside somewhere that will prevent someone accidentally getting their hands in the acid. Do not breath the fumes. After five minutes remove the acid and sand it again, and then coat it again with the 14K. This is the only time you will have to do this. You may hear many exotic methods of removing built up streaks on the stone, but simple sanding with 400 sandpaper is the best and actually will improve the testing surface for future metals testing
PRELIMINARY SCREEN USING THE MAGNET:
The kit now comes with an extremely powerful 32 pound pull magnet. If you have an old kit with the relatively weak doughnut magnet, we strongly recommend you buy this new powerful magnet for $3, and we sell an even stronger one with a 55 pound pull for $5 that we use in the store. It will save you a lot of money. All the kits we sell now come with the 32 pound pull magnet. When the customer lays out items from her jewelry box on the counter silver or gold colored, touch the magnet on each item. Anything that leaps to the magnet is either pure nickel or has strong iron content. Refuse these without further testing. Spring rings and lobster claw clasps have steel springs and will be attracted to the magnet; ignore this. Any items that are mildly attracted to the magnet require more scrutiny than items that don’t. Heavily plated rhodium items, such as the charms on charm bracelets will be mildly attracted to a strong magnet. On these pieces that are mildly attracted to the magnet, we recommend taking a file and cutting deeply into the metal. Of course you should explain to the customer why and what you intend to do before proceeding. Apply the 14K acid to the cut. If it bubbles green, the item is not gold or silver. Rhodium plated items will bubble green so it is important to scrape the surface clean with a file. If it turns a light milky gray it is at least 90% silver. If it turns brown with very light green bubbles it is 8K gold or below. If it just turns brown with no bubbles it is likely 10K gold. If it does not change color it is likely 14K gold or better. 10K white gold will normally bubble green when the acid is applied. Test it on the stone to confirm that it is 10K gold.
Use the following instructions provided here for further testing.
CAUTION: Most plated and gold filled items and most costume jewelry WILL NOT be attracted to the magnet. The preliminary screening is basically a time saving test to eliminate items that are obviously not gold or silver and also to point out “suspicious items”. Normal testing as outlined throughout this document is still required.
TEST FOR 10K GOLD: Rub item being tested on a well sanded smooth test stone, leaving a strong visible streak. Apply 10K acid. Observe the reaction.
(1) If test mark fades completely, item has zero gold content. If the test mark stays bright it is at least 10K gold.
(2) If the test mark stays on the stone but fades to brown, the item is less than 10K but has some definite gold content. To determine approximate gold content, proceed to the destructive test for 10K gold. Often a comparison test is helpful. Rub a 10K class ring on the stone with the unknown next to it, and see how much the item being tested fades when acid is applied to both at the same time.
DESTRUCTIVE TEST FOR 10K GOLD: File into the metal. Apply 14K (Not 10K!) acid directly upon the cut.
(1) Both white and yellow gold metal: If the cut immediately and profusely bubbles very green, the item is gold filled or gold plated and the metal is copper, nickel or some brass alloy.
(2) If the application of the 14K acid on to the cut or filed flat surface causes the yellow metal to turn brown but after 10-15 seconds there are no green bubbles, then the item tested is true 10K gold. Observation of the green bubbles is best examined with a ten power loupe. This can also be confirmed by blotting the acid with a white Kleenex. The green will be visible on the tissue. If after 10 seconds there are only a few green bubbles the item is 9K. If there are numerous green bubbles after 10 seconds the item is about 8K. If bubbles appear instantly the item is 7 karat or less. If there are profuse bubbles the item is 6K or below.
Remember: The information in this paragraph is applicable only after the streak faded but not completely with the 10K acid.
Note: True 10K white gold will very slightly bubble green when the 14K acid is applied. This is normal due to the high nickel alloy.
TEST FOR 14K GOLD: Rub item on the test stone forming a strong streak. Apply 14K acid to the streak:
(1) If test mark stays on the stone with no fading after ten seconds the metal is at least 14K. If it fades completely there is no gold content. If it fades away to brown with no green bubbles is is surely solid 10K.
(2) If test streak stays on the stone but immediately fades to brown, the metal is considerably lower than 14K. On most American jewelry it is very likely 10K. Note: Some jewelry with a factory stamp may be actually slightly less than 14K. Prior to about 1982 it was legal to stamp 13.5K gold as 14K. 13.5K will cause only slight change in the streak, causing it to lose some brightness and after a while turn a rusty yellow. You will encounter some jewelry marked 14K P. This means 14K “plumb” gold, exactly 14K gold.
Note: 14K “pink” or “rose” gold and 14K white gold usually tests a slight bit weaker than yellow gold, in most all tests.
TEST FOR 18K GOLD: Rub item on a clean spot on a well sanded test stone.
Apply the 18K acid.
(1) If test mark immediately goes “lights out” to brown the unknown is almost surely 14K (If it has passed the previous 14K tests.) No further testing is necessary. It is not 18K.
(2) If the test mark stays on the stone for 10 seconds or so and then slowly fades to brown is it likely just some under karated 18K. This could be 16K or 17K as a result of some manufacturer or maker cheating on the metal alloy. This is not uncommon.
(3) If the test mark is unaffected by the acid and remains bright on the stone, it is at least 18K. If you are testing white metal and suspect the item is platinum, proceed to the test for platinum. If an unmarked item has a more of a goldish-yellow color, and “heft” for size than is typical for 18K gold, refer to testing for 22-24 karat gold.
TESTING FOR GOLD FILLED: You may encounter items belonging to a customer that have no karat stamps and you suspect might be gold filled. Ask the customer’s permission to test it on the stone. Rub a sharp corner or edge on the stone. Then rub another strong streak, from the same edge or corner right next to the first streak. Then do it a third time, all three next to each other. Apply the same 14K acid to all the streaks. If the second or third streak fades out or significantly changes color the piece is heavy gold filled. On most gold filled one streak is all that is needed. If it fades away completely there is no gold content. If you art still skeptical, cut into the piece with a file and apply the 14K acid and look for green bubbles.
TEST FOR 21 TO 24K GOLD: Assaying 21-24K is the most difficult of all tests. The best way is to rub a streak from a known 21 or 22K coin and a streak of the unknown, side by side. Apply 22K or platinum acid. The lower karat metal will fade first. This takes some practice and educated guessing. If the item tested is said to be 24K rub it on the stone. If you get a nice smooth even streak it is not 24K. Pure gold will not “bite” into the stone. It will be impossible to get a nice even streak and might leave little flecks of gold on the stone.
TEST FOR PLATINUM: Rub item on stone. Apply 22K or platinum acid. Observe reaction.
If item gradually fades to brown it is surely 18K, (presuming is has already passed the 18K test). If the white metal remains on the stone after a minute or so with no trace of fading, the metal is platinum.
Important notice! This is where you should start using your head. Genuine platinum should rub relatively soft on the stone and should have a much more than average heft or heavy feeling relative to its size. If the item is so hard that it practically squeaks across the stone, it can’t be platinum. Iron and steel items will pass the stone test for platinum. Use the magnet provided in the kit to eliminate these. There are many other white non-magnetic metals that will give false platinum stone readings, such as metals used in stainless flatware, “seladium” class rings, chromium cobalt dental material, etc.
There are numerous thick heavy wedding bands out there that are factory stamped PLATINUM. Unfortunately, for those who buy these, they are some sort of worthless white stainless metal. These thick rings deceptively heavy but only because they are so thick.
50% PLATINUM JEWELRY: This is something new, just started around 2005. It is platinum alloyed with some other metal as a cheaper substitute for platinum jewelry. It is usually marked .500 PT. It tests platinum on the black stone using both 22K and platinum acid. If someone polished out the karat stamp it would be extremely difficult to distinguish it from regular platinum jewelry. The only slight clue is that it doesn’t quite feel heavy enough to be regular platinum. However, this is something only the most sophisticated, experienced metals dealer would pick up on. There is hardly any of this out there as of 2009 when this was written, but it is something to be aware of and to look out for. We have only ever seen and tested one .500PT piece.
PALLADIUM TESTING:Rub item on stone and apply 18K or 22K acid. If the metal has palladium content, the streak will very slowly turn a yellowish green color. If streak fades completely it is not palladium.
TEST FOR SILVER USING RED ACID: Clean the surface of the test item. The test will be better if the surface has been scraped with the flat of a knife or a file. Apply red silver acid on the cleaned area; the brighter the red color, the higher the silver content. Experimentation with the red acid will be helpful. The shelf life of the red acid is sometimes a limited.
Should you need to tell if a piece is 80% or 90% or.925 or .999, find a known piece of the above and drop the red acid on the surface. Note the brightness of the known samples and compare them to the unknown. We actually prefer the following tests for silver.
NON DESTRUCTIVE TEST FOR SILVER USING 18K ACID: Rub unknown white metal on the stone. A smoothly sanded stone is essential for this test. Apply 18K acid to the streak, observe reaction. If test mark turns to a silvery blue color, there is strong silver content. If test mark turns to a blotchy uneven blue color it is silver plate. If it dissolves completely it has no silver content. Even silver coins that are just 10% pure will leave some faint blue streaks or faint blobs. A false silver reading may be obtained if the item being tested is very heavy silver plate or a Sheffield (silver filled) process.
DESTRUCTIVE SILVER TESTS: Take a file or knife to a smooth flat area of item being tested. Go as deep as possible depending upon the value of the item being tested and the circumstances. Then drop 14K acid on the spot. If the metal is 90% or higher the spot will turn a whitish milky gray color, it will likely be.925 sterling silver. The whiter the color, the higher the silver content. If the spot turns a noticably darker gray color the silver is approximately 80%. The darker the color the lower the silver content.
If the silver is below 60% green bubbles will form. If the bubbles are immediate and very green and profuse the item is not solid silver. Silver below 80% is rarely encountered in jewelry or silverware.
COMPARISON TESTS: One of the best ways to determine karat values is to rub a standard item (test needles, or 14K band or 10K class ring, or 22K coin, etc.) on the stone and the unknown item next to it. Drop the most applicable test acid on both streaks at the same time. The weaker will fade first. Some assayers keep a small 10K and 14K ring as standards.
TESTING FOR DENTAL MATERIALS: Little testing is usually required for yellow dental gold as it is so obvious. A large group of dental gold will average to about 16K gold, and most metals buyers accept dental material based on assumed 16K without any testing, but individual pieces vary. It is usually useless to attempt to get an accurate karat number using the stone and acid as the alloys dental labs use palladium, ruthenium, platinum, and other exotic metals that make this material test higher than it really is.
WHITE DENTAL MATERIAL: Extremely hard, silvery white metals used in modern bridges are made of chromium cobalt and other alloys and contain no precious metals, nor do they have any value. This material is impervious to all acids. White metal teeth are made up of silver, palladium and a little gold. These will test as 14K or 18K on the stone but this is a false reading. White dental teeth will usually have a gold content of 5-20%, a palladium content of about 10-20%, and a small percentage of silver. The remainder will be dental lab alloys of non precious metal.
BRITISH COMMONWEALTH .375 & .333 GOLD:
These are usually from Great Britain, Australia, New Zealand and S. Africa and are symbols for 9K and 8K gold. We have tested some of these that were significantly under karated. Use the destructive tests for 10K if in doubt here.
PLACER GOLD AND NATURAL NUGGETS: These are very hard to figure as they contain mineral impurities which vary depending upon where they are from. Most pacer flakes will assay at around 80% pure. Most nuggets are higher karat but contain more impurities and assays will vary from 70-90%. Many dealers buy both at 18K. None will be 24K as is the common public belief.
CREMATORY DENTAL MATERIAL: Dealers may encounter dental material recovered from crematoriums. These are teeth and bridges that are burned dark and are sometimes partially or completely melted. Use extreme caution here. While most dental material is accepted at face, there are other prosthesis metals contained in bodies that are melted along with teeth but contain no precious metals. Many of these look like melted teeth. Some are copper nickel or brass and will bubble green when 14K acid is applied. Each piece should be carefully tested.
X-RAY RECOVERY SILVER: Properly processed, dry x-ray recovery silver will assay to about 90-95%, but losses of 10-20% or more, before-after melt are common due to an amalgam that evaporates during melting. The flaky, crusty, silverish material is always higher than the black dirt type that looks like potting soil. Caution: Buying the black dirt x-ray material is quite risky. If it is improperly processed or if it is damp, the actual silver content per after-melt ounce can be quite low.
INDUSTRIAL CONTACT POINTS: Most of these show good strength on all the silver tests, however hardly any refineries will accept them. When they are melted some toxic gas is released due to cadium and sometimes cyanide content. It is best to pass on these unless you find some refinery or other dealer who will buy them from you, or you can really buy them very dirt cheap. Note: We buy silver contact points.
MELTED DOWN LUMPS: Take a triangular file and go deep. Apply 14K acid to the cut. If there are no green bubbles use the stone and acid to determine the karat. The lump should be tested in more than one place as improper melting can cause different readings on different parts of the lump. Large thick lumps are problems as the centers may contain non precious metals.
THAILAND BAHT CHAINS:These are identified by the higher karat yellow color, exceptional heavy heft, and the omega shaped clasp. Some are marked 24K or .999, and others .965 near the clasp. Some have no markings. There are only two types. One is what is called “Thai Gold”, which is .965 fine (23.16K). The other type is pure gold (24K). It is very easy to tell them apart. The 23.16K will leave a nice continuous solid rub on the stone. No further testing is usually necessary. The 24K is so soft it will not bite into the stone, will not make a good streak and small flakes of gold might be evident on the stone. Most of the more recent 23K chains are stamped near the clasp, 965. Some of the older ones that are only 23K are stamped 24K or .999. Testing is required.
JEWELRY MARKED 417: Somewhere around 1980, jewelry marked 417 started to appear on the market. Plumb 10K would be .416666 fine, so .417 should be an indication for plumb 10K, however this is not always true. We have tested more than 20,000 pennyweights of jewelry marked 417 and it is our estimate that about 30% of it is actually 10K; 50% is 8-9K, and 20% is 7K or lower. Use the 10K destructive test previously explained on all that is marked 417.
COMMONLY ENCOUNTERED BOGUS ITEMS:
HEAVY ITALIAN BRACELETS: These are extremely well made, beautiful, usually multi colored pieces of jewelry. They feel like gold due to their thickness and large width and have convincing dual factory stamps, 750 18K. The bogus ones are usually very lightly gold plated over base metal. A simple 18K stone test is all that is needed.
THAILAND PRINCESS RINGS: These are the dome shaped rings with multi layers of semiprecious stones. The semi precious stones are almost always real and they are universally stamped 18K. It is uncommon to find one of these that are actually 18K. Most are 10K or much less. A simple stone test is all that is needed.
HAND STAMPED GOLD JEWELRY: Many rings, bracelets and other jewelry are non factory and are occasionally under karated by the maker. A good example of this is the heavy Cuban link bracelets and necklaces coming out of Miami. Many of these are stamped 18K and test stronger than 14K but much weaker than 18K. The bad ones are typically about 16K. Some stamped 14K test only about 12K. Most factory stamps and hallmarked items are correct. As you gain experience, you will get a feeling for the ones that require further testing, despite the factory stamps.
STAMPS AND HALLMARKS ON SILVERWARE: Use extreme care in buying silverware items (bowls, trays, pitchers, etc.) stamped by hand. They are almost sure to be silver plate and stamped to deceive. Note: If a modern American silver maker places its name and trademark on a sterling silver item, it will be clearly marked STERLING. Similar foreign items will be marked STERLING or 925. English silver has the “passant lion” symbol for sterling somewhere included in the hallmark. This is a little lion with one paw up.
Older European silver might be marked 835 or 800 (83.5% and 80%). All of the silver just mentioned is rarely under karated. If American or foreign silver items include the capital letters EP (Electro Plate), or EPC (Electro Plated Copper), or EPNS (Electro Plated Nickel Silver), or any combination of letters including EP, then the items are silver plated and not solid silver. No testing is necessary.
UNSTAMPED SILVER JEWELRY: American Indian jewelry is seldom stamped. Most all Indians buy their stock from supply houses and most of it is good sterling silver. Little testing is usually required if the piece looks right. Mexican jewelry stamped 925 sterling is usually OK but there are exceptions. The fake stuff turns a silvery faint yellow color with age and is easy to spot. A simple stone-18K test is all that is needed. Well made properly stamped American silver jewelry is seldom underkarated or bogus.
If it looks right, it probably is. The magnet test is very important when buying a large lot of silver jewelry. Use the magnet provided in the test kit. Items that are attracted to it are not solid silver. Again, with experience you will get a feeling about which items require actual testing.
POCKET WATCH CASES: Many antique or vintage gold filled pocket watch cases have factory stamps or inscriptions that read for example, “14K Dueber Special”, which means the watches are filled with 14K gold. Most but not all genuine solid gold watches will have a factory hallmark with the inscription, “Warranted 14K US Assay”. Solid gold cases are relatively thin. Gold filled watch cases are usually very thick and rigid. Push on the back of the case with your thumbs. If it “gives a little”, it has a very good chance of being solid gold. If it is stiff as a board it is very likely gold filled. The best gold filled cases are very heavy gold filled. If testing on the stone use the multiple streak as outlined in the previous, Testing for 14K Gold Filled section. Many watch cases are stamped 5 Year up to 25 year. The five and ten year cases are just a little bit better than light gold plated. The 20 year and 25 year cases or ones marked extra are very heavy gold filled and can be sold to scrap dealers by the ounce.
DOLLAR SIZED COUNTERFEIT COINS:
In recent times (2000 to date) there are a great abundance of pure nickel counterfeit coins, US and Chinese silver dollars, other world silver dollars, etc, sold at flea markets, garage sales and such. These would not likely fool any experienced coin dealer, but to the average person they really look good. For some unknown reason most all that we have seen are made of pure nickel, therefore they will be strongly attracted to any magnet, even the ones off your refrigerator at home. These originate in China and are prolific in Asian flea markets, night markets, street vendors, etc. Note: Just because a coin passes the magnet test, it doesn’t mean it is genuine. There are some deceptive counterfeits out there made of silver alloy and copper-nickel that do not attract to a magnet, even the super strong one provided in the newer test kits and the other even our stronger
55 pound pull magnet.
HIGH GRADE CHINESE COUNTERFEIT COINS
Since about year 2000, Chinese counterfeiters have been making large silver
coins: US Trade Dollars, US Bust dollars, Seated dollars, rare date Morgan dollars, and other expensive coins of the world including old rare Chinese coins. These are completely different from those in the previous paragraph which are very apparently junk that even a casual collectgor would spot. In most cases these excellent counterfeits are made of the correct silver content and correct weight. They are die struck coins made from counterfeit or forged dies, and are extremely deceptive and some are very difficult to detect, even by experienced coin dealers. Be very wary if someone offers you large dollar sized coins of considerable value. Many of these are purchased on ebay and such, some directly from China at apparent bargain prices; most all are bogus.
NEW JEWELRY MARKED 925 CHINA:
We were recently offered a big lot of new “silver” chains and bracelets factory stamped 925 China. Normally, these would pass without inspection but they were mildly attracted to the powerful magnet. We cut into one, applied the 14K acid and discovered that they were all very heavy silver plate.
HEAVY FIGARO CHAINS MARKED 925:
These have factory type marks and stamped 925. The clue to further testing is that they are mildly attracted to the newer powerful magnets. When cut into and 14 acid applied they bubble green. These are high quality looking necklaces and bracelets, look great, would fool anyone who doesn’t do the acid test.
HANDY TIPS AND ADVICE SILVER STAMPS AND HALLMARKS
If a piece, flatware or hollowware, is American made and there is a hallmark or a maker’s name, if it DOES NOT read sterling, then you can be 100% sure that it is silver plate or such. No American company would make something sterling and forget to stamp it STERLING. If it reads German Silver, or Alaska Silver, or Deep Silver, Brazil Silver, or other nefarious silver pseudonyms, it is not silver. A quick way to tell, even flatware without looking, is try to bend the piece. If it is stiff as a board and would bend only with brute force, then it is not silver. If you try to bend an item and it “gives a little”, then it is probably silver.
British and British commonwealth sterling will have hallmarks and within the little squares there will be a little lion, three feet on the ground and front paw up. This is called the passant lion and is how English sterling items are marked. In those same little squares you might see the letters EP. This means Electro Plate. On some flatware you might see the “rampant lion”. This one is standing on two back feet and paws up. This is not a symbol for sterling, just the opposite, always silver plate
In older Europe the standard for silverware, hollowware and jewelry was 80% and 83%. These will be marked 800 and 830 or 835. You will also see German flatware marked 90. These are never silver, always silver plate. Use the “try to bend” test to confirm this.
You might encounter older European hollowware and even some flatware that has no markings or unidentifiable hallmarks. Take the piece and rub it on the black stone; make three or more rubs side by side from the same place on the item; then you apply the 18K acid to all three streaks. If all three turn an even blue color, you can be pretty sure the item is at least 80% silver. If the last couple streaks on the stone are less blue or fading out, you are reading indications for silver plate. Caution: Sheffield plate has very thin sheets of silver over base metal. You really have to get a good rub of five or more streaks to get through the plates.
Once you are sure the item is really silver, you won’t know the percentage unless you actually apply acid directly on the item. Find an inconspicuous place; scrape the surface with the flat of a knife or file; and apply 14K acid. Only 14K! If the area turns a light milky gray color then it is very likely sterling silver. If it turns an off color darker gray it is likely 800 or 830 silver. If it bubbles light green but not profusely it is 60% silver or less. Profuse green bubbling means you better recheck what you did because it is probably silver plate. Pewter will produce gray bubbling. Of course if this item is just scrap or you have permission from the customer, don’t waste time on the stone. Take the flat of a big ugly file and go deep. Apply the 14K acid and observe the reaction.
HEAVY 18K WHITE GOLD NECKLACES
In early 2009 heavy 18K white gold items have been offered to dealers all over the US, quite often by Hispanic people. Most of these are very long, heavy neck chains and bracelets, and even heavy pendants and items that would be attached to a key chain. Due to their size and thickness they feel heavy like genuine 18K gold. These test good when 18K acid is applied to the streak on the touchstone, and that the streak fades slowly when 22K acid is applied. This is a “perfect” test for good 18K gold, but don’t be fooled!
It has been reported they also test good on the electronic metal testers and they ARE NOT attracted to a magnet. Typical content is 69% iron, 14% cromium, 10% nickel, manganese, copper and mocybdenum. This may be a custom formula created to fool all precious metals testing. It is an Austenitic stainless alloy, all magnetic properties have been removed by heating to 1100 degrees Celsius Genuine 18K white gold chains and other heavy items are seldom seen so it is likely if you are offered any, they will be fake. All these bogus pieces are brand new and have a brilliant chrome-like luster. Be extremely cautious if you are offered any. It is probably better to just pass on all heavy 18K white gold items as described here than risk a big loss. We know of no way to actually test, yes or no, on these new bogus pieces.
GOLD LEAF AND POWDER:
Most gold leaf comes in paper packets, the little strips of ultra fragile gold are between thin sheets of paper. Holding the packet in the palm of your hand the heft is there, but it is 99+% only the weight of the paper.
The sheets of gold are so thin they are hard to remove. There is hardly any recoverable gold. Do not be fooled into paying any decent money as the whole packet will go into the GF refinery bowl. 99% of the “gold powder”
has zero gold content. Take a pinch of it and place it on the black stone. Stand back and apply a drop of 14K acid and you will likely see a big green flash, indicating no gold content. Watch out for the toxic fumes. Should you encounter some that do not flash green, don’t react to the acid, do not buy it until it has been melted into a lump so you can test it on the black stone.
GRAMS PENNWEIGHTS AND TROY OUNCES
One troy ounce = 31.103 grams or 20 Pennyweight To convert grams to pennyweight divide by 1.555 To convert pennyweight to grams multiply by 1.555 A troy pound is 12 troy ounces (obsolete term) A regular pound contains 14.58 troy ounces A kilogram (1000 grams) is 32.15 troy ounces A one carat diamond weighs .2 grams
Tips on Testing 21K 22K 23K 24K:
TESTING HIGH KARAT GOLD FROM AROUND THE WORLD:
The most difficult metals to assay are 21, 22 and 24K gold.
21K: This is the standard for jewelry in Dubai, Saudi Arabia and other Middle Eastern countries. These are often stamped 21 but the characters are Arabic. If you see a hallmark with Arabic writing and amongst it (7 1) with the 7 pointed to the right (reversed), it is Arabic for 21 (21K). If you see a 1 and inverted “V” it is Arabic for 18(K).
The penalty for making jewelry and gold items in that part of the world with a bogus karat stamp is cutting someone’s hand off, so if you see 21K in Arabic as explained above, it is probably right on the indicated karat stamp. The piece should be a very yellow gold, and have a strong “heft”.
Should you want to test it on the stone, make a good streak and apply 22K acid. It should very slowly start to fade away. If “the lights go out”, fades out almost immediately, it is not 21K gold.
22K: This is the standard for jewelry made in India and some South American countries and English gold circa:1700′s. Unfortunately, it is seldom stamped and some of the 22K stamps are bogus. This should be a very yellow color and heavy to the heft. The test here is to make a streak on the black stone from a known piece of 22K gold (a British Soverign or some standard 22K coin or piece of jewelry you know to be definitely 22K).
Then rub the piece being tested next to it on the stone. Apply 22K acid to both streaks simultaneously. Observe the reaction to the acid. If the item being tested fades very slowly, the same as the known 22K, then it is 22K gold. No further testing needed. If the streak of the piece being tested fades more, then it is probably 21K or slightly lower. If the “lights go out” then the item is probably 18K.
23.16K: This is the standard for Thailand style baht chains. Many of these are stamped 965 (965 X 24K = 23.16K), and if stamped 965 are almost sure to be right on the money. If in doubt use the 22K comparison test recommended above. Unfortunately many of these have no karat stamp. To further complicate things these baht style Thai chains are occasionally made in 24K.
Use the 24K test in the following paragraph to detirmine if the chain is 24K. If you rub .965 gold on the stone you will be able to get a nice smooth streak with no problem and will be able to tell .965 gold from 24K.
24K: 24K (also sometimes stamped .999) gold is very soft. When rubbing it on the stone, it will not “bite” and it will be difficult getting a nice smooth streak. The appearance on the stone will be more yellow goldish color than lower karats. Sometimes when rubbing 24K on the stone, microscopic little flakes of gold will be visible on the stone.
Note:
Belleair Coins Inc sells the very best complete metals testing kits (not the Ebay crap), and many different sizes of black testing stones, acids, magnets, and just about anything a dealer might need to test and assay gold, silver, platinum, palladium.
MAGNETS AND SILVER BARS
Some have tried to test the authenticity of .999 silver bars, especially the larger ones and have discovered that there is a strange reaction when a strong rare earth magnet is passed closely over the top of the bar. When you run a magnet past a conductor (silver being an almost perfect conductor) it generates electricity, a series of very strong “eddy” currents within the bar, slightly repelling the magnet creating a counter (EMF) Electro Magnetic Force. EMF is the force that causes motors and electric generators to function. Actually, there is no reason to test a silver bar with any kind of magnet. If you think a silver bar is bogus, balance it on a stack of coins and strike an end with a metal object. If it rings is is probably OK. If there is a “thunk”, then you have problems.
Information in this pamphlet is based on Art Arbutine’s experiencies buying of scrap gold, silver, platinum, palladium, etc from the public and dealers for the past 36 years.
This is copyright 2009 and cannot be copied in whole or part without the express consent of Belleair Coins Inc, 1350 W Bay, Largo Fl 33770, (727) 585-4502, art@belleaircoins.com.
