Here's what I found: Austria, 20 Corona (Crown) 21.20 mm 6.7751g .900 fine .196 ounces of gold Restruck to this day
You did not buy a 20 Korona, but a ducat. Still a restrike, but only containing 3,8 g of gold and sold as buillion.
Woops, I should of took a better look at the coin. It's a 1 ducat with only .1106 gold content. Here is what a 20 krona looks like: