Wow, what a beautiful coin. Your coin contains (no surprise) 37.5 grams of pure gold (oro puro), and this is where it gets its value. To figure out this value, first convert grams to troy ounces:
37.5 grams / 31.1 grams per troy ounce = 1.205 troy ounces
Now look up the value of pure gold on a web site like kitco.com
gold 'spot' value at the time of this writing = $1407 US dollars per troy ounce
1.205 ounces x $1400 per ounce = about $1700
Kitco reports the current 'spot' value of gold, which is pure bullion value. If your coin is in excellent condition, you can add a small amount, say $20, to the value to account for the fact that the gold has been minted into a nice looking coin.
If you have an absolutely pristine, fully uncirculated coin, the catalogs report a premium above the gold value of about $500 for all dates except 1947. Coins dated 1947 are more common in high grades and do not have this added premium.
The spot value of gold changes every minute. Look up the price right now! If you are buying or selling from a gold dealer, he or she will invoke a commission to handle the transaction.