FACT: She didn't need to.
After years of preparation for his first voyage, Columbus did approach – and was turned down by – the kings of Portugal, France, and England for funding, which is probably how this myth originated.
In the end, Spain’s King Ferdinand and Queen Isabella agreed to finance his journey. While Isabella may have suggested selling the jewels at some point, her advisers assured her there were other ways to finance Columbus’s journey.
The best way to get money, they told her, was to make the city of Palos pay back a debt to the crown by providing two of the ships. Another way was to get Italian financial backing for part of the expenses. Ultimately, the crown put up very little money from the Spanish treasury.