Zac hit it pretty close. what we run into is you can get the diameter easy enough, most are in metric sizes because it's easier to do the math on them. Look for any numbers at all on the hub of the prop, that narrows thing down really fast. Some companies make props in the same diameter but with different pitches and applications. Some have a constant pitch and others a progressive pitch. There are lifting, low-lift and non-lifting props. This is why the numbers on a prop hub are so important, especially for us that do not own pitch guages.
Here's a little light but not much.
An example. Octura uses "X" to denote a low-lift prop. The next number such as a "4" shows that the pitch is 1.4 times the diameter of the prop which is the last two numbers. An X-437 would have a diameter of 37mm and a pitch of 51.8mm . If it has a 14, 16, 19, etc. before the last two numbers then it is a lifting prop. now use the 1.4, 1.6, 1.9 times the diameter to find the pitch.