1972 Bahamas $20 gold

[LMB]

On the page that lists the coins that the RCM produced for the Bahamas, the 1972 $20 gold coin is listed as having a gross weight of 6.48 grams. Link here: https://www.coinsandcanada.com/coins-ar ... int&id=719

I'm questioning if this is correct? There are several reasons to think that it should be 6.38g or 6.39g.

Reason #1 By comparing to the other gold coins in the 4-coin set, each one has the same ratio of gold to the coin face value. If we start with the $100 coin it weighs 31.95g. Based on that, the $50 dollar should weigh half (31.95 * 0.5 = 15.975), and yes, it shows as 15.97g. If we look at the $10 coin, it has exactly 1/10 of the weight. or 3.195g (rounded to 3.2g). Now for the $20 it should be .2 of 31.95 or 6.39g

Reason #2 Other websites list the weight as 6.38g: link here https://en.numista.com/catalogue/pieces90318.html

Reason #3: the world coin book (2004) has conflicting numbers. It states the Actual Gold Value at .1880oz. This makes sense if the weight is 6.38oz. (6.38 x 0.917 = 5.85g fine weight), and converting to troy ounces 5.85 / 31.1035 = 0.188. The conflicting part is that the book has the weight at 6.48g. It could be that the world coin book is the source of the incorrect number of 6.48g.

Reason #4. I have one of the $20 coins and it weighs in at 6.41 / 6.42 grams (which is closer to 6.39 than 6.48).

Any thoughts?
p.s. Yes, the difference is very small between 6.38 and 6.48, and does not make much of a difference. just trying to get precise numbers.

Thanks!

[coinguy]

NGC has it listed at 6.48 g also.
It is possible that Numista made a typo or had the wrong info. I would go by the RCM weight as it is they who produced the coin. If you look at the chart you referenced, you will see that on different denominations that
the weight varies from year to year. Not sure what the +- tolerance is for that particular year but even if it is
only .1g, you would be within spec.

[LMB]

I was not aware that the source for that page was the RCM itself. I assumed that someone had taken the time to piece the information together. Good to know the tolerance on the weights. Thanks for the reply!