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Bill Watson's Gold Ring Vdi Chart, With Notes From Steve H


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5 hours ago, mcjtom said:

The low karatage of most of the rings didn't seem to make much difference (or actually could contribute to increasing the VIDs due to relatively higher conductivity of low-grade 9K alloy - see the gold alloys conductivity chart above). 

It may be more to do with size and mass of the rings than conductivity. I am sure no expert, but that is what I see on the ones I find. The thinner, smaller, finer rings tend to hit lower VDI while the large heavy men’s rings hit higher and harder.

Low VDI for me are sure pretty, but they do not weigh up.

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4 hours ago, DOOGY-MD said:

Is there any way to correlate F75 or F19 VDI numbers to Bills chart?

Well, certainly if those exact targets were re-measured with these detectors.  But you can get in the ballpark by comparing common coins.  A USA 5-cent piece gets a dTID of 12-13 in the ML Eqx (probably closer to 13 than 12 for fresh drops) while the USA 1-cent Zincoln is 21 when freshly dropped (and goes down from there with time in the ground due to galvanic corrosion.

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Thank you bro!

But are the scales a one to one comparison or some other exponential logarithmic relationship?

Just asking...

I guessed 48-68 VDI on the Fisher scale??

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10 minutes ago, DOOGY-MD said:

But are the scales a one to one comparison or some other exponential logarithmic relationship?

I'll let you do the math.  Equinox VDI's for USA copper cent and clad dime are 25-26.  For the USA quarter its 29-30 (for fresh drop probably closer to 30).  Now that you have four datapoints you can figure out whether the relationship between scales is linear, logarithmic, or something else.

12 minutes ago, DOOGY-MD said:

I guessed 48-68 VDI on the Fisher scale??

I assume you're referring to the F19 (and Gold Bug family) VDI's.  I haven't used mine in a long while so I won't quote a VDI (but if you have one, you can air test to get them).  On the Fisher F75 a USA nickel is around 30.  (I don't have the other coins' VDI's burned in my memory as they are shown across the top of the detector's display.)

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2 minutes ago, mcjtom said:

Out of curiosity: is this coin different from 'the US copper penny'?  Which one is the modern, copper-coloured 1 cent coin?

In 1982 the composition was changed from 95% copper 5% zinc to 2.5% copper, 97.5% zinc.  We call these more recent cents 'Zincolns' and that is what (when not deteriorated) gives a 21 VDI on the Equinox.

It's not easy to tell the difference between the two by sight (except for Zincolns that have been in the ground several years), although some people are adept at that.  Date is a giveaway (as long as you realize that both compositions have the 1982 date, but only that one year).  Weight is another distinguishing feature since the 95% copper version is heavier -- ~3.1 g vs. ~2.6 g. for the Zincoln.

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23 hours ago, DOOGY-MD said:

Is there any way to correlate F75 or F19 VDI numbers to Bills chart?

This may be useful if you want to compare the F75 to some other detectors.

Gold Ring VDIs.PNG

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Wow! Thank you Mical!

Great work!

It looks like the Deus VDI numbers are closest to my F19.....for some reason...

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