What metal impurity makes rubies red and emeralds green?

More Questions:

In the restaurant world, what does "Blue-plate special" refer to?

Speed Skating originated in which part of the world?

Pubs are said to have evolved from what Anglo-Saxon establishment that started to appear in the 5th century?

What university presents the annual Pulitzer Prize journalism awards?

How did Scarlett and Rhett’s daughter die, in "Gone with the Wind"?

Who is the subject of the book "Longitude" by Dava Sobel?

Which US city was author J. D .Salinger born in?

Buenos Aires is the capital of what country?

In the TV show "The Simpsons', who normally drives Springfield Elementary's school bus?

What was the first full feature film directed by George Lucas?

Vaselina and Brillantino were alternate names which film?

In medieval times, what was an Iron Maiden used for?

Which century saw the appearance of playing cards?

What is the fear of glass known as?

A 8 to 12 mph wind on the Beaufort scale is called what?