The Brasher Doubloon:
The High Window,
Chapter 2 and throughout

"A rare gold coin called a Brasher Doubloon."

The Brasher Doubloon

The Brasher Doubloon is a real coin, and the information Elisha Morningstar gives Marlowe in Chapter 7 is accurate. In the 1940s, the price of a Brasher Doubloon ranged from $6,000 to $12,000.