Size and weight

I recently acquired one of these medals. However mine weighs 19.3g  with a diameter of  34mm. The one listed here on Numista weighs less.

I did find some information on a Heritage auctions that states that there was a silver and gold sets that were sold. In the silver set there is a single coin with the same design mine has that measures and weighs the same. 

I am looking for some more information or possibly i need to add it to Numista if it is a different type.

https://coins.ha.com/itm/expositions-and-fairs/seattle-world-s-fair-complete-20-piece-gold-and-silver-sets-total-20-medals-/a/427-81549.s

"Silver matching set. The silver set is identical to the above medals except for the size and weight of the large silver medal, 64.0 mm, 156.4 gm. The size and weight of the medium medals are 40 mm, 30 gm. The small silver medal is 34 mm, 19.4 gm.
We sold a certified gold set in our Platinum Night sale, January 2007, lot 3906, for more than $25,000."

I have a book that has a lot of information about these medals.

National Commemorative Medals of the United States Since 1873

Unfortunately I am not home at the moment. It will be several days before I can get the information.

From the book mentioned above.

Gold 14kt .5833 fine 341 grains - 4 mintage. Grains to Grams 22.1

Silver .900 fine 300 grains - 10,015 mintage. Grains to Grams 19.44

Bronze 250 grains - 140,000 mintage. Grains to Grams 16.20

An unknown number of bronze medals were sold by private vendors that were silver plated. 

Please create a new page for a solid silver variety and I will be make changes to the current page with this information since it would be the silver-plated variety based on the information in the book.

I have requested all members be moved to undetermined.

Move members to undetermined – Numista