VDI of Silver??? Better Think Twice! (Part 1)

[Neil in West Jersey]

We all read the forums and the manuals which tell us that gold will have low VDI numbers, while silver will have a high VDI number. Well last night I decided to test a box filled with 30 different types of jewelry; assorted silver and gold chains and pendants, to see what one could really expect.

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While many of the results were predictable, there were some surprises, especially when it came to silver. I am not speaking of tiny silver charms either. I am talking about significant sized pieces of silver jewelry. Another point is one that I made before; that delicate gold chains can come in as low as -30 on the V3i, so if you are not accepting into the negative numbers you may be missing small gold chains.

I am in the process of putting all of the results into a spreadsheet with links to photos (or maybe I will create a new photo gallery on my site with the info), but here are some of the more surprising results:

Silver Charm Necklace: VDI= 12-14
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Thin 14K Bracelet: VDI Bounce from -30 to +4
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Silver Bracelet: VDI = 20
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Heavy Italian Silver Bracelet: VDI=24-30
[attachment 200909 021.JPG]

Men's Silver Bracelet: VDI= 50
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[Neil in West Jersey]

Silver Bangle: VDI = 42 when flat, 69 on edge
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Tiffany & Co. Silver "Mail" Ring: VDI=7(!!!)
[attachment 200913 030.JPG]

Heavy Silver Box Chain: VDI=8
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All Testing was done with a 5.3 inch "Shooter" coil at 22.5KHz (normalized) with RX at 3 and other sensitivities turned down to compensate for EMI. Sensitivity was raised on a few delicate gold items which did not respond at the lower sensitivity.

I hope this information is useful!

 

[MANDAD76]

Great info - thanks for postin'!!!

 

[kyledfx]

cool info, but why not 3 frequency 22.5 seems to hit weak on silver [ uk guys think otherwise] the same items with 3 frequency color response would be super helpful, as i assume most run 3 frequency at parks and homesites.

 

[Neil in West Jersey]

cool info, but why not 3 frequency 22.5 seems to hit weak on silver [ uk guys think otherwise] the same items with 3 frequency color response would be super helpful, as i assume most run 3 frequency at parks and homesites.

The only reason this was done in 22.5KHz was because the test was done indoors and this frequency limited the EMI. Using a different frequency should not have an affect on the VDI numbers as long as it is normalized. This was not a sensitivity test, however I will check this in Best Date this afternoon to see if there is any difference.

 

[Aaron]

Thanks alot Neil, good to know stuff! I found one of those silver mail rings, exactly like yours, thought it was silver, but when it came up low VDI thought it was aluminum but was so heavy. I wonder what I did with it?.......

 

[Neil in West Jersey]

Here is the result in Best Data, showing the dominant frequency in Pinpoint and the Search screen for the Tiffany ring, which came in at 7 VDI in 22.5KHz. As you can see the VDI is still basically the same, but you can also see that it hit strongest in 22.5KHz.

In short heavy silver rings and coins will hit hardest in 2.5KHz, while smaller jewelry including silver will hit harder in other frequencies.

Conversely, heavy gold objects, such as Gold Eagles and Double Eagles will hit hardest in 2.5KHz.

This is the main reason that our friends on the other side of the pond look for hammered silver coins using 22.5KHz.

Thanks for your input

 

[Rob (IL)]

I've posted this before several times from my notes. pretty much the same.
Frequency
Best Frequency to Use is determined not only by metal content, but also size and thickness. For thicker coins with high silver content there is no question that 2.5 kHz will hit harder than 22.5 kHz. For US nickels 22.5 kHz will hit hardest. 22.5 kHz may also work best on small thin coins, even those with high silver content, due to skin effect. High frequency may also work best on low silver content coinage. 7.5 kHz is typically better on copper coins. Test the detector for the items you want to find. If all you want is US silver, then you should use 2.5 kHz. If all you want are thin gold rings or small nuggets, then select 22.5 kHz. If you want the best depth on a wide range of targets, use 3 frequencies. Carl

 

[kyledfx]

thanks for the info. some very practical tests.

 

[Neil in West Jersey]

Thanks alot Neil, good to know stuff! I found one of those silver mail rings, exactly like yours, thought it was silver, but when it came up low VDI thought it was aluminum but was so heavy. I wonder what I did with it?.......

I am glad you found the info helpful. The ring is what I would call a medium to heavy weight ring, so it is not the total weight that determines the VDI, more likely the density. A small silver charm which weighs much less than the ring comes in the 50 VDI range.

 

[Jim D]

Hello Guys , I have found 4 or 5 silver rings and a silver bracelet since last August. One of the rings was a mans heavy silver that came in at
86 to 87 vdi in 3 frenq , all others rings is smaller + bracelet came in around 80 to 83vdi, all hit harder in the 2.5.

 

[Neil in West Jersey]

Hello Guys , I have found 4 or 5 silver rings and a silver bracelet since last August. One of the rings was a mans heavy silver that came in at
86 to 87 vdi in 3 frenq , all others rings is smaller + bracelet came in around 80 to 83vdi, all hit harder in the 2.5.

All of my rings that were tested hit hard in the same range as your when they were solid, dense rings. The Tiffany & Co. ring is actually made up of hundreds of tiny rings so it does not have the density that the turquoise ring has, even though it is more than three times the weight. Many bracelets have similar characteristics to the Tiffany ring.

Tiffany & Co Ring (Weight=8.01 grams) VDI=7
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Small Women's Silver Ring (Weight 2.4 grams) VDI=83)
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[jbow]

I have checked Mexican silver before and most of it read low... I cannot imagine why. I wonder if that is the case here.

Julien

 

[grumpyjohn]

Here in the U.K.silver hammered coins show up in the foil/pull tab range so if using discrim. every thing above -21 I accept or risk the chance of missing the wee rascals!!

 

[Neil in West Jersey]

Here in the U.K.silver hammered coins show up in the foil/pull tab range so if using discrim. every thing above -21 I accept or risk the chance of missing the wee rascals!!

Very wise advise! Pewter buttons have a tendency to read below zero as well, so any relic hunters should be aware.

 

[burlbark]

I have checked Mexican silver before and most of it read low... I cannot imagine why. I wonder if that is the case here.

Julien

Mexican Silver is often Alpaca or German silver. These both contain zero silver and are comprised of tin and copper.

On another note I found a silver pepper or salt shaker top 20 min ago.... It was on the surface and I thought it was can slaw until I picked it up. 3.5 grams and vdi at around a 60....

 

[gilfordberry]

Most of the silver I've found comes in the dime-quarter VDI area. I tend to trust the VDI more than the "silver" (925 or sterling) labeling. Probably 25% or more of the "silver" jewelry simply isn't silver. Ditto for gold - and I'm not talking about gold electroplate or gold filled, either. In testing gold for our club, I find that probably 75 percent or more of rings marked 10k, 14k, or 18k test low - 10k rings at 6 or 8k, 14k usually around 12k, and 18k more often than not at 16k. When a ring shows up marked 14KP it usually is, though. (P as in "plumb" - exactly 14k) It may not be so bad in other parts of the country, but my proximity to the Mexico border means a lot of Mexican-made jewelry shows up here, and it's usually less than indicated. They've even gone to the trouble of marketing brass chains stamped "14k Italy". Even your diamond rings may not be diamonds even though they cut glass and diamond test as diamond. Ever heard of moissanite? You can't trust anyone these days.

 

[gilfordberry]

The low VDIs from the Tiffany ring and box chain are easy to explain. Remember that the receive coil is seeing the return signal from the target, which is generated by the currents induced into the target by the transmit coil. The current path for excited electrons in the ring and the chain would be many small loops (one in each segment of the chain or ring) and the algebraic sum of all those small signals is what the detector sees....depending on the phase and signal strength of each small signal, the return overall signal could be anywhere. This is the same reason that small fine chains are so hard to detect - the net signal generated is often dirty and of low signal strength. The fact that the earring is not a complete circle explains its lower VDI. Try this: put a piece of copper or silver wire on the earring to "complete the circle"...then retest to see what your VDI is.......... I'm not the expert here, but this is how I see it....

 

[Larry (IL)]

I think your eyesight is pretty good. Detectors sees segmented targets as not one big one, but many tiny targets close to each other.