The 1903-S Half Dollar is a typical date in the series -- not particularly rare; affordable; and easy to find in most grades. In terms of production quality, two issues will vex the collector: the strike is sometimes weak on the upper right corner of the shield and on the eagle's wing in that area; and, on many examples, particularly those in high grade, roller marks can be seen on one or both sides. Roller marks arise from the planchet manufacturing process. To produce planchets, bars and strips of silver are squeezed between rollers until they reach the proper thickness. Any defects or wear lines on the rollers will transfer to the metal itself. If, during the striking process, the pressure is set too low, the transferred lines and defects will not be obliterated. Not all 1903-S Half Dollars have roller marks, and some of the best examples have them. Not unexpectedly, the coins with roller marks will often have a weaker-than-optimum strike. Given the option (assuming it is even available), collectors should choose fully-struck examples as free of roller marks as possible.
The finest 1903-S Half Dollar is the PCGS MS68 example from the Eliasberg Collection (there catalogued as a raw MS66). Collector J.M. Clapp obtained the coin directly from the San Francsico Mint in 1903.