Prop identification.  Most manufacturers mark the propeller with prop diameter, pitch and shaft diameter. Often the letter R or L for right or left hand will appear in the marking. A prop marked 12r7x1 would be a 12 inch diameter right hand 7 pitch prop for a 1” shaft. The markings will vary a bit between manufacturers the same prop could also be 127R1from a different manufacturer. Folding and feathering props may have individual blades marked in a similar fashion. By measuring the prop diameter and shaft diameter it is usually easy to figure out which is the pitch marking on the prop.    A two blade Prop diameter is easily measured, Just a tape measurement across the tips is all that is needed. for a three blade prop the centerline of the hole to one tip is measured for the radius of the prop then doubled to get the diameter. The diameters are usually in inch increments. Pitch is difficult to measure without special equipment and the markings must be relied upon to specify pitch..
    The USA (sae) shaft diameters are usually ¾”, 7/8”, 1” 1 1/8, and 1 ¼. The shaft can be measured just behind the prop or close to where the shaft exits the hull using a rule or caliper. If the prop is not mounted on a shaft the shaft diameter cannot be directly measured because the propeller bore is tapered and changes sizes. However by measuring the smallest diameter in the bore of the propeller the shaft size can be determined from the chart below.
Shaft dia     smallest bore dia    keywidth
  0.750                    0.608              0.187
  0.875                    0.710              0.250
  1.000                    0.812              0.250
  1.125                    0.913              0.250
  1.250                    1.015              0.312

    Right or left hand prop.



 
FIG 1 right hand propellers

If you look at the prop as mounted on the boat. and you are looking forward from the stern of the boat to the bow. If the edge of the prop is the farthest away from you is on the right the prop is right hand rotation. If the prop is off the boat and you are looking at the smallest bore diameter and the edge of the prop is the farthest away from you is on the right the prop is right hand rotation.    

So a few simple measurements can determine most of the needed information about a prop, only the pitch cannot be measured. but with the measured dimensions of the prop the pitch can usually be determined form the remaining markings on the prop. However a word of caution about bronze props  many have been repitched after manufacture without a change to the marking.