The Knight's Cross
The Ritterkreuz was the highest award for valor in the German military. Most were awarded to officers for the success of their units in combat, but it could also be earned by personnel of any rank for acts of extreme bravery in battle. Repeated successes were rewarded with subsequent awards attached to the Knight's Cross. In order or precedence they were oak leaves, swords, and diamonds. There were only 27 recipients of the diamonds making it a rather rare award.
There were two grades higher than the diamonds, but only one of each was ever awarded during the War. Hans-Ulrich Rudel was awarded golden oakleaves, and Hermann Goring had the oversized Grand Cross awarded to himself.
Field Note: Many soldiers wore an Iron Cross 2nd class with a neck ribbon in combat and kept their Knight's Crosses at home.
Original Knight's Crosses are made from silver and can fetch well over $10,000. These reproductions are of good but are not "museum" (aka counterfeit) quality. High quality, three-piece silver reproductions exist, but they cost several hundred dollars and the difference is not discernible except on very close examination.