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Posted 03/01/2016 12:24 pm
gxseries I believe that both coins have gone to the LCS. The coin with the hole in it was the first coin that the LCS saw and it looks legitimate. The question was regarding the second coin which I estimated should weigh 26.8 grams (now confirmed).
I agree that a hole makes a difference but the effect on weight can be calculated in the case of the hole. The surface area of the hole expressed as a percentage of the surface area of the entire coin multiplied by the weight of the coin provides a good estimate of the silver lost.
When using this method make sure the hole was drilled and not simply made by driving a nail through the coin. A hole made by driving a nail through a coin usually results in minimal weight loss. Also allow for any build-up of metal around the drill hole by reducing the estimate.
I do this by blowing up a picture of the coin. I have a large screen so I was able to make the coin 275 mm (about 11 inches) in diameter. I always check to make sure the coins struck in collar (like this one) are round. Measure the diameter horizontally and vertically to determine any distortion. Average the diameter.
Then do the same for the hole. Results 274 mm coin - 14 mm hole.
The factor pie (3.14159) can be eliminated so the ratio of the squares of the radii are all you need.
The radius of the coin is 137mm and the hole 7mm.
The squares are 18,769 and 49 so the amount of weight lost due to the hole is 49/18769 or 0.00261 just over one quarter of a percent. Weight loss would be about 0.07 gram.
Making a guess before making the calculation - I would be willing to guess that most collectors would over estimate the weight loss due to the hole.
When dealing with coins do not rely on your senses alone but rather make calculations whenever possible that others can check. This way you are doing your best to avoid common mistakes of over-estimating weight loss due to wear and damage.
I agree that a hole makes a difference but the effect on weight can be calculated in the case of the hole. The surface area of the hole expressed as a percentage of the surface area of the entire coin multiplied by the weight of the coin provides a good estimate of the silver lost.
When using this method make sure the hole was drilled and not simply made by driving a nail through the coin. A hole made by driving a nail through a coin usually results in minimal weight loss. Also allow for any build-up of metal around the drill hole by reducing the estimate.
I do this by blowing up a picture of the coin. I have a large screen so I was able to make the coin 275 mm (about 11 inches) in diameter. I always check to make sure the coins struck in collar (like this one) are round. Measure the diameter horizontally and vertically to determine any distortion. Average the diameter.
Then do the same for the hole. Results 274 mm coin - 14 mm hole.
The factor pie (3.14159) can be eliminated so the ratio of the squares of the radii are all you need.
The radius of the coin is 137mm and the hole 7mm.
The squares are 18,769 and 49 so the amount of weight lost due to the hole is 49/18769 or 0.00261 just over one quarter of a percent. Weight loss would be about 0.07 gram.
Making a guess before making the calculation - I would be willing to guess that most collectors would over estimate the weight loss due to the hole.
When dealing with coins do not rely on your senses alone but rather make calculations whenever possible that others can check. This way you are doing your best to avoid common mistakes of over-estimating weight loss due to wear and damage.
Thanks, Bob! Now figuring out this I never thought of actually calculating the stuff out like that. That way, I can get pretty close to what the weight should be with holed coins. At least one more step I can take to figure if they are legitimate or not! I love the knowledgeable and helpful people of this forum 
