A little tip on buying a used wheel. Always know the pitch & diameter that is was casted in. This is important so you as the 2nd buyer know if it can be adjusted to your specs.
The best way to tell on most quality wheels is the stamping. On a quality wheel the original manufacture usually stamps the diameter & pitch between the blades on the rounded surface of the hub. This is a difficult stamp. Therefore when wheels are re-pitch or diameter is changed the prop shops usually stamp the wheel on the flat rear surface of the hub.
Know what you are buying. Wheels that have been re-pitched more that once should be avoided.