Another question about $20 St Gaudens v. bullion $50 American Gold Eagle

I am preparing the educational segment for my local coin club's next meeting. The topic I thought I'd speak on for 5 minutes is the difference between the the original $20 St Gaudens and the modern bullion version, the $50 American Gold Eagle.

So far I've found this (http://home.comcast.net/~reidgold/saint/page10.html), but I'd like to be able to address why the $20 St Gaudens has a larger diameter and is thinner than the bullion $50 American Gold Eagle? I suspect it has something to do with the size, shape and dimensions of other contemporary bullion coins being issued by other govts/mints (Kruggerands, Maples, Pandas).

Does anyone have a link or source I can check out on this topic? I have googled it, but and coming up empty.

Thanks. :thumb:

 

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Your question has got me interested and I love a challenge. Both coins are for all practical purposes cylinders. I don't have the dimensions but I will look them up. We know that the AGE is 91.67% gold and is one troy ounce. The SG is 90% gold and 0.9675 a troy ounce of gold.

The cylinder formula is π*r^2*h . I smell a spreadsheet!

 

I don't know why, but your response made me smile. :thumb: Hopefully, we can figure this thing out and it will be an interesting educational topic at my meeting next Wednesday.