While the "Maltese Falcon" itself is fictional the object might have been inspired by a real one - albeit one with something without the exciting Knights Templar and Pirates(!) backstory. The "Kniphausen Hawk" is a bejeweled drinking vessel dating to at least 1697 and is currently owned by the Duke of Devonshire, being ~15 inches high and literally covered in gemstones it would certainly fit the bill (pun intended!) but it has nothing to do with Malta or Algiers and I've not been able to find any evidence to show that Hammet was aware of the Kniphausen Hawk.