I was watching Schindler's List and one scene confused me - what was the reason for the swallowing diamonds scene?
So they would not be confiscated by the Nazis.
In the second world war, the Nazis raided the homes of both the Jewish population in Germany and the the population of citizens from other cities and countries they have invaded. They stole any valuables they could find, including gold and diamonds. This was then used to help fund the Nazi war machine.
By swallowing the diamonds, the family was trying to keep them in their possession. They would later "pass" the diamonds, and would still be able to use them (e.g. for buying provisions, smuggling themselves, sentimental value, etc).
You can read a fascinating account of a real Holocaust survivor who claims to have done something similar here.