In Kraków during World War II, the Germans had forced local Polish Jews into the overcrowded Kraków Ghetto. Oskar Schindler, an ethnic German, arrives in the city hoping to make his fortune. A member of the Nazi Party, Schindler lavishes bribes on Wehrmacht (German armed forces) and SS officials and acquires a factory to produce enamelware. To help him run the business, Schindler enlists the aid of Itzhak Stern, a local Jewish official who has contacts with black marketeers and the Jewish business community. Stern helps Schindler arrange financing for the factory. Schindler maintains friendly relations with the Nazis and enjoys wealth and status as "Herr Direktor", and Stern handles administration. Schindler hires Jewish workers because they cost less, while Stern ensures that as many people as possible are deemed essential to the German war effort, which saves them from being transported to concentration camps or killed.
SS-Untersturmführer (second lieutenant) Amon Göth arrives in Kraków to oversee construction of Płaszów concentration camp. When the camp is completed, he orders the ghetto liquidated. Many people are shot and killed in the process of emptying the ghetto. Schindler witnesses the massacre and is profoundly affected. He particularly notices a tiny girl in a red coat – one of the few splashes of color in the black-and-white film – as she hides from the Nazis, and later sees her body (identifiable by the red coat) among those on a wagon load of corpses. Schindler is careful to maintain his friendship with Göth and, through bribery and lavish gifts, continues to enjoy SS support. Göth brutally mistreats his maid and randomly shoots people from the balcony of his villa, and the prisoners are in constant fear for their lives. As time passes, Schindler's focus shifts from making money to trying to save as many lives as possible. To better protect his workers, Schindler bribes Göth into allowing him to build a sub-camp.
As the Germans begin to lose the war, Göth is ordered to ship the remaining Jews at Płaszów to Auschwitz concentration camp. Schindler asks Göth to allow him to move his workers to a new munitions factory he plans to build in his home town of Zwittau-Brinnlitz. Göth agrees, but charges a huge bribe. Schindler and Stern create "Schindler's List" – a list of people to be transferred to Brinnlitz and thus saved from transport to Auschwitz.
The train carrying the women and children is accidentally redirected to Auschwitz-Birkenau; Schindler bribes Rudolf Höss, the commandant of Auschwitz, with a bag of diamonds to win their release. At the new factory, Schindler forbids the SS guards to enter the production rooms and encourages the Jews to observe the Jewish Sabbath. He spends much of his fortune bribing Nazi officials and buying shell casings from other companies; his factory does not produce any usable armaments during its seven months of operation. Schindler runs out of money in 1945, just as Germany surrenders, ending the war in Europe.
As a Nazi Party member and war profiteer, Schindler must flee the advancing Red Army to avoid capture. The SS guards in Schindler's factory have been ordered to kill the Jews, but Schindler persuades them not to, so that they can "return to their families as men, instead of murderers." He bids farewell to his workers and prepares to head west, hoping to surrender to the Americans. The workers give Schindler a signed statement attesting to his role saving Jewish lives, together with a ring engraved with a Talmudic quotation: "Whoever saves one life saves the world entire." Schindler is touched but is also deeply ashamed, as he feels he should have done even more. As the Schindlerjuden (Schindler Jews) wake up the next morning, a Soviet soldier announces that they have been liberated. The Jews leave the factory and walk to a nearby town.
Following scenes depicting Göth's execution after the war and a summary of Schindler's later life, the black-and-white frame changes to a color shot of actual Schindlerjuden at Schindler's grave in Jerusalem. Accompanied by the actors who portrayed them, the Schindlerjuden place stones on the grave. In the final shot, Neeson places a pair of roses on the grave.

Question: On what do the workers engrave the quotation, "Whoever saves one life saves the world entire"?
Answer: A ring.